use hemplate::Hemplate;
use hemx::{Html, IntoEffect};
use hemx_axum::Form;
use hemx_host::{
    browser_pwa_host_profile, native_shell_host_profile, Capability, CapabilityManifest,
    CapabilityShape, CapabilityUse, HapticPattern, HostCall, HostCallId, HostEvent, HostFailure,
    HostFailureKind, SharePayload as HostShareData,
};
use std::collections::VecDeque;
use std::sync::{Arc, Mutex};

#[hemx::surface]
pub mod ui {}

#[derive(Clone, Debug, PartialEq)]
pub struct ExercisePlan {
    pub name: &'static str,
    pub target_sets: u8,
    pub reps: u8,
    pub kg: f32,
}

#[derive(Clone, Debug, PartialEq)]
pub enum WorkoutCommand {
    CompleteSet,
    StartNextSet,
    FinishWorkout,
    ChangeWeight { kg: f32 },
    CorrectLastSet { kg: f32 },
    SkipExercise,
    RecordNote { text: String },
    UndoLastAction,
}

#[derive(Clone, Debug, PartialEq)]
pub enum WorkoutEvent {
    SetCompleted {
        exercise: String,
        set: u8,
        reps: u8,
        kg: f32,
    },
    RestFinished {
        exercise: String,
        set: u8,
    },
    WeightChanged {
        exercise: String,
        kg: f32,
    },
    SetEdited {
        exercise: String,
        set: u8,
        kg: f32,
    },
    ExerciseSkipped {
        exercise: String,
    },
    NoteRecorded {
        text: String,
    },
    WorkoutFinished {
        completed_sets: u8,
        total_sets: u8,
    },
}

#[derive(Clone, Debug, PartialEq)]
pub enum WorkoutPhase {
    Ready,
    Resting,
    ReadyToFinish,
    Finished,
}

#[derive(Clone, Debug, PartialEq)]
pub struct WorkoutProjection {
    pub current_exercise: usize,
    pub completed_sets_for_current: u8,
    pub total_completed_sets: u8,
    pub phase: WorkoutPhase,
    pub next_action: String,
    pub primary_action: String,
    pub progress: String,
    pub exported: bool,
}

#[derive(Clone, Debug)]
pub struct WorkoutState {
    pub plan: Vec<ExercisePlan>,
    pub commands: Vec<WorkoutCommand>,
    pub events: Vec<WorkoutEvent>,
    pub projection: WorkoutProjection,
    pub activity: VecDeque<String>,
    pub host_status: String,
}

#[derive(Clone)]
pub struct AppState {
    workout: Arc<Mutex<WorkoutState>>,
}

impl AppState {
    pub fn demo() -> Self {
        Self {
            workout: Arc::new(Mutex::new(WorkoutState::demo())),
        }
    }

    pub fn with_workout<R>(&self, f: impl FnOnce(&WorkoutState) -> R) -> R {
        let workout = self.workout.lock().unwrap();
        f(&workout)
    }

    fn update<R>(&self, f: impl FnOnce(&mut WorkoutState) -> R) -> R {
        let mut workout = self.workout.lock().unwrap();
        f(&mut workout)
    }
}

impl WorkoutState {
    pub fn demo() -> Self {
        let mut state = Self {
            plan: demo_plan(),
            commands: Vec::new(),
            events: Vec::new(),
            projection: WorkoutProjection::start(),
            activity: VecDeque::new(),
            host_status: "Ready to keep the session private until you export.".into(),
        };
        state.refresh_next_action();
        state
    }

    fn primary_command(&self) -> WorkoutCommand {
        match self.projection.phase {
            WorkoutPhase::Ready => WorkoutCommand::CompleteSet,
            WorkoutPhase::Resting => WorkoutCommand::StartNextSet,
            WorkoutPhase::ReadyToFinish | WorkoutPhase::Finished => WorkoutCommand::FinishWorkout,
        }
    }

    fn accept(&mut self, command: WorkoutCommand) -> Option<WorkoutEvent> {
        // req: local/001 req: local/004
        let event = self.validate(&command)?;
        self.commands.push(command);
        self.events.push(event.clone());
        self.project(&event);
        Some(event)
    }

    fn validate(&self, command: &WorkoutCommand) -> Option<WorkoutEvent> {
        match command {
            WorkoutCommand::CompleteSet if self.projection.phase == WorkoutPhase::Ready => {
                let exercise = self.current_exercise()?;
                Some(WorkoutEvent::SetCompleted {
                    exercise: exercise.name.into(),
                    set: self.projection.completed_sets_for_current + 1,
                    reps: exercise.reps,
                    kg: exercise.kg,
                })
            }
            WorkoutCommand::StartNextSet if self.projection.phase == WorkoutPhase::Resting => {
                let (exercise, set) = self.next_ready_target()?;
                Some(WorkoutEvent::RestFinished {
                    exercise: exercise.into(),
                    set,
                })
            }
            WorkoutCommand::FinishWorkout
                if self.projection.phase == WorkoutPhase::ReadyToFinish =>
            {
                Some(WorkoutEvent::WorkoutFinished {
                    completed_sets: self.projection.total_completed_sets,
                    total_sets: self.total_target_sets(),
                })
            }
            WorkoutCommand::ChangeWeight { kg } if kg.is_finite() && *kg >= 0.0 => {
                let index = self.editable_exercise_index()?;
                let exercise = self.plan.get(index)?;
                Some(WorkoutEvent::WeightChanged {
                    exercise: exercise.name.into(),
                    kg: *kg,
                })
            }
            WorkoutCommand::CorrectLastSet { kg } if kg.is_finite() && *kg >= 0.0 => self
                .last_completed_set()
                .map(|(exercise, set)| WorkoutEvent::SetEdited {
                    exercise,
                    set,
                    kg: *kg,
                }),
            WorkoutCommand::SkipExercise if self.projection.phase != WorkoutPhase::Finished => {
                let exercise = self.current_exercise()?;
                Some(WorkoutEvent::ExerciseSkipped {
                    exercise: exercise.name.into(),
                })
            }
            WorkoutCommand::RecordNote { text } if !text.trim().is_empty() => {
                Some(WorkoutEvent::NoteRecorded {
                    text: text.trim().into(),
                })
            }
            _ => None,
        }
    }

    fn project(&mut self, event: &WorkoutEvent) {
        // req: local/001 req: local/004
        match event {
            WorkoutEvent::SetCompleted { exercise, set, .. } => {
                if let Some(index) = self.exercise_index(exercise) {
                    self.projection.current_exercise = index;
                }
                self.projection.completed_sets_for_current = *set;
                self.projection.total_completed_sets = self
                    .projection
                    .total_completed_sets
                    .saturating_add(1)
                    .min(self.total_target_sets());
                self.projection.phase =
                    if self.projection.total_completed_sets >= self.total_target_sets() {
                        WorkoutPhase::ReadyToFinish
                    } else {
                        WorkoutPhase::Resting
                    };
            }
            WorkoutEvent::RestFinished { exercise, .. } => {
                if let Some(index) = self.exercise_index(exercise) {
                    self.projection.current_exercise = index;
                    self.projection.completed_sets_for_current =
                        completed_sets_for(&self.events, exercise);
                }
                self.projection.phase = WorkoutPhase::Ready;
            }
            WorkoutEvent::WeightChanged { exercise, kg }
            | WorkoutEvent::SetEdited { exercise, kg, .. } => {
                if let Some(index) = self.exercise_index(exercise) {
                    self.plan[index].kg = *kg;
                }
            }
            WorkoutEvent::ExerciseSkipped { exercise } => {
                let next = self
                    .exercise_index(exercise)
                    .unwrap_or(self.projection.current_exercise)
                    + 1;
                self.projection.current_exercise = next;
                self.projection.completed_sets_for_current = 0;
                self.projection.phase = if next >= self.plan.len() {
                    WorkoutPhase::ReadyToFinish
                } else {
                    WorkoutPhase::Ready
                };
            }
            WorkoutEvent::NoteRecorded { .. } => {}
            WorkoutEvent::WorkoutFinished { .. } => {
                self.projection.phase = WorkoutPhase::Finished;
            }
        }
        self.refresh_next_action();
        self.activity.push_front(event.summary());
        while self.activity.len() > 5 {
            self.activity.pop_back();
        }
    }

    fn undo_last_event(&mut self) -> Option<String> {
        // req: local/001 req: local/004
        self.commands.push(WorkoutCommand::UndoLastAction);
        let removed = self.events.pop()?;
        let summary = removed.summary();
        self.rebuild_projection();
        self.activity.push_front(format!("undid {summary}"));
        while self.activity.len() > 5 {
            self.activity.pop_back();
        }
        Some(summary)
    }

    fn rebuild_projection(&mut self) {
        let events = self.events.clone();
        let host_status = self.host_status.clone();
        let exported = self.projection.exported;
        self.plan = demo_plan();
        self.projection = WorkoutProjection::start();
        self.projection.exported = exported;
        self.activity.clear();
        self.refresh_next_action();
        for event in &events {
            self.project(event);
        }
        self.host_status = host_status;
    }

    fn refresh_next_action(&mut self) {
        self.projection.progress = self.progress_text();
        match self.projection.phase {
            WorkoutPhase::Ready => {
                if let Some(exercise) = self.current_exercise() {
                    let name = exercise.name;
                    let target_sets = exercise.target_sets;
                    let reps = exercise.reps;
                    let kg = exercise.kg;
                    self.projection.primary_action = "Complete set".into();
                    self.projection.next_action = format!(
                        "Next: {name} set {}/{} · {reps} reps · {kg} kg",
                        self.projection.completed_sets_for_current + 1,
                        target_sets,
                    );
                } else {
                    self.projection.phase = WorkoutPhase::ReadyToFinish;
                    self.refresh_next_action();
                }
            }
            WorkoutPhase::Resting => {
                let target = self
                    .next_ready_target()
                    .map(|(exercise, set)| format!("{exercise} set {set}"))
                    .unwrap_or_else(|| "finish workout".into());
                self.projection.primary_action = format!("Start {target}");
                self.projection.next_action = format!("Rest 90s · next: {target}");
            }
            WorkoutPhase::ReadyToFinish => {
                self.projection.primary_action = "Finish workout".into();
                self.projection.next_action =
                    "Workout complete · finish and export your session".into();
            }
            WorkoutPhase::Finished => {
                self.projection.primary_action = "Session saved".into();
                self.projection.next_action = "Session saved · export or replay anytime".into();
            }
        }
    }

    fn current_exercise(&self) -> Option<&ExercisePlan> {
        self.plan.get(self.projection.current_exercise)
    }

    fn editable_exercise_index(&self) -> Option<usize> {
        match self.projection.phase {
            WorkoutPhase::Finished | WorkoutPhase::ReadyToFinish => None,
            WorkoutPhase::Resting
                if self.current_exercise().is_some_and(|exercise| {
                    self.projection.completed_sets_for_current >= exercise.target_sets
                }) =>
            {
                (self.projection.current_exercise + 1 < self.plan.len())
                    .then_some(self.projection.current_exercise + 1)
            }
            _ => self
                .current_exercise()
                .map(|_| self.projection.current_exercise),
        }
    }

    fn exercise_index(&self, name: &str) -> Option<usize> {
        self.plan.iter().position(|exercise| exercise.name == name)
    }

    fn last_completed_set(&self) -> Option<(String, u8)> {
        self.events.iter().rev().find_map(|event| match event {
            WorkoutEvent::SetCompleted { exercise, set, .. } => Some((exercise.clone(), *set)),
            _ => None,
        })
    }

    fn next_ready_target(&self) -> Option<(&'static str, u8)> {
        let exercise = self.current_exercise()?;
        if self.projection.completed_sets_for_current >= exercise.target_sets {
            let next = self.plan.get(self.projection.current_exercise + 1)?;
            Some((next.name, 1))
        } else {
            Some((
                exercise.name,
                self.projection.completed_sets_for_current + 1,
            ))
        }
    }

    fn total_target_sets(&self) -> u8 {
        self.plan.iter().map(|exercise| exercise.target_sets).sum()
    }

    fn progress_text(&self) -> String {
        let total = self.total_target_sets().max(1);
        let done = self.projection.total_completed_sets.min(total);
        let percent = u16::from(done) * 100 / u16::from(total);
        format!("{done} of {total} sets · {percent}% complete")
    }

    pub fn event_log_text(&self) -> String {
        if self.events.is_empty() {
            return "No session events yet.".into();
        }
        self.events
            .iter()
            .enumerate()
            .map(|(index, event)| format!("{}: {}", index + 1, event.summary()))
            .collect::<Vec<_>>()
            .join("\n")
    }

    pub fn export_event_log(&self) -> String {
        // req: local/003
        self.events
            .iter()
            .map(WorkoutEvent::to_export_line)
            .collect::<Vec<_>>()
            .join("\n")
    }

    fn replay_export(&mut self, export: &str) -> Result<usize, String> {
        // req: local/001 req: local/003 req: local/004
        let lines = export
            .lines()
            .filter(|line| !line.trim().is_empty())
            .collect::<Vec<_>>();
        if lines.is_empty() {
            return Err("nothing to replay yet; complete a set first".into());
        }

        let mut events = Vec::with_capacity(lines.len());
        for (index, line) in lines.iter().enumerate() {
            let event = WorkoutEvent::from_export_line(line)
                .ok_or_else(|| format!("line {} is not a workout event", index + 1))?;
            events.push(event);
        }

        let mut replayed = WorkoutState::demo();
        for event in &events {
            replayed.events.push(event.clone());
            replayed.project(event);
        }
        replayed.host_status = format!(
            "Replayed {} exported events into a fresh projection; app policy still owns sync.",
            events.len()
        );
        *self = replayed;
        Ok(events.len())
    }

    fn recovery_text(&self) -> String {
        match self.activity.front() {
            Some(last) if last.starts_with("started ") => {
                format!("Last action: {last}. If that was a double tap, Undo returns to rest.")
            }
            Some(last) if last.starts_with("changed ") || last.starts_with("corrected ") => {
                format!("Last action: {last}. Undo restores the previous plan.")
            }
            Some(last) if last.starts_with("skipped ") => {
                format!("Last action: {last}. Undo restores the skipped exercise.")
            }
            Some(last) if last.starts_with("undid ") => {
                format!("Recovery complete: {last}. Continue from the restored next action.")
            }
            Some(last) => format!("Last action: {last}. Undo is available."),
            None => "Undo appears here after your first session event.".into(),
        }
    }
}

impl WorkoutProjection {
    fn start() -> Self {
        Self {
            current_exercise: 0,
            completed_sets_for_current: 0,
            total_completed_sets: 0,
            phase: WorkoutPhase::Ready,
            next_action: String::new(),
            primary_action: String::new(),
            progress: String::new(),
            exported: false,
        }
    }
}

fn demo_plan() -> Vec<ExercisePlan> {
    vec![
        ExercisePlan {
            name: "Goblet squat",
            target_sets: 3,
            reps: 8,
            kg: 24.0,
        },
        ExercisePlan {
            name: "Push-up",
            target_sets: 2,
            reps: 10,
            kg: 0.0,
        },
    ]
}

fn completed_sets_for(events: &[WorkoutEvent], exercise: &str) -> u8 {
    events
        .iter()
        .filter_map(|event| match event {
            WorkoutEvent::SetCompleted {
                exercise: event_exercise,
                set,
                ..
            } if event_exercise == exercise => Some(*set),
            _ => None,
        })
        .max()
        .unwrap_or(0)
}

fn export_field(value: &str) -> String {
    value.replace(['\t', '\n', '\r'], " ")
}

impl WorkoutEvent {
    fn summary(&self) -> String {
        match self {
            Self::SetCompleted {
                exercise,
                set,
                reps,
                kg,
            } => {
                format!("completed {exercise} set {set}: {reps} reps @ {kg} kg")
            }
            Self::RestFinished { exercise, set } => format!("started {exercise} set {set}"),
            Self::WeightChanged { exercise, kg } => format!("changed {exercise} to {kg} kg"),
            Self::SetEdited { exercise, set, kg } => {
                format!("corrected {exercise} set {set} to {kg} kg")
            }
            Self::ExerciseSkipped { exercise } => format!("skipped {exercise}"),
            Self::NoteRecorded { text } => format!("note: {text}"),
            Self::WorkoutFinished {
                completed_sets,
                total_sets,
            } => format!("finished workout: {completed_sets}/{total_sets} sets complete"),
        }
    }

    fn to_export_line(&self) -> String {
        // req: local/003
        match self {
            Self::SetCompleted {
                exercise,
                set,
                reps,
                kg,
            } => format!(
                "set_completed\t{}\t{set}\t{reps}\t{kg}",
                export_field(exercise)
            ),
            Self::RestFinished { exercise, set } => {
                format!("rest_finished\t{}\t{set}", export_field(exercise))
            }
            Self::WeightChanged { exercise, kg } => {
                format!("weight_changed\t{}\t{kg}", export_field(exercise))
            }
            Self::SetEdited { exercise, set, kg } => {
                format!("set_edited\t{}\t{set}\t{kg}", export_field(exercise))
            }
            Self::ExerciseSkipped { exercise } => {
                format!("exercise_skipped\t{}", export_field(exercise))
            }
            Self::NoteRecorded { text } => format!("note_recorded\t{}", export_field(text)),
            Self::WorkoutFinished {
                completed_sets,
                total_sets,
            } => format!("workout_finished\t{completed_sets}\t{total_sets}"),
        }
    }

    fn from_export_line(line: &str) -> Option<Self> {
        // req: local/003
        let fields = line.split('\t').collect::<Vec<_>>();
        match fields.as_slice() {
            ["set_completed", exercise, set, reps, kg] => Some(Self::SetCompleted {
                exercise: (*exercise).into(),
                set: set.parse().ok()?,
                reps: reps.parse().ok()?,
                kg: kg.parse().ok()?,
            }),
            ["rest_finished", exercise, set] => Some(Self::RestFinished {
                exercise: (*exercise).into(),
                set: set.parse().ok()?,
            }),
            ["weight_changed", exercise, kg] => Some(Self::WeightChanged {
                exercise: (*exercise).into(),
                kg: kg.parse().ok()?,
            }),
            ["set_edited", exercise, set, kg] => Some(Self::SetEdited {
                exercise: (*exercise).into(),
                set: set.parse().ok()?,
                kg: kg.parse().ok()?,
            }),
            ["exercise_skipped", exercise] => Some(Self::ExerciseSkipped {
                exercise: (*exercise).into(),
            }),
            ["note_recorded", text] => Some(Self::NoteRecorded {
                text: (*text).into(),
            }),
            ["workout_finished", completed_sets, total_sets] => Some(Self::WorkoutFinished {
                completed_sets: completed_sets.parse().ok()?,
                total_sets: total_sets.parse().ok()?,
            }),
            _ => None,
        }
    }
}

#[derive(Hemplate)]
pub struct Workout {
    pub next_action: String,
    pub primary_action: String,
    pub status: String,
    pub progress: String,
    pub recovery_status: String,
    pub finish_title: String,
    pub finish_copy: String,
    pub share_action: String,
    pub event_log: String,
    pub export_payload: String,
    pub host_status: String,
}

#[derive(Hemplate)]
pub struct AppShell {
    pub runtime_src: &'static str,
    pub body: Html,
}

pub fn page(runtime_src: &'static str, state: &WorkoutState) -> Html {
    ui::page(&AppShell {
        runtime_src,
        body: render(state),
    })
}

pub fn view(state: &WorkoutState) -> Workout {
    let export = state.export_event_log();
    let has_events = !state.events.is_empty();
    let (finish_title, finish_copy, share_action) = match state.projection.phase {
        WorkoutPhase::Ready | WorkoutPhase::Resting if !has_events => (
            "Finish unlocks as you train".into(),
            "Complete a set to create a replayable local export.".into(),
            "Export after first set".into(),
        ),
        WorkoutPhase::Ready | WorkoutPhase::Resting => (
            "Session log is ready".into(),
            "Your progress is already replayable; finish all sets for the final export moment.".into(),
            "Share current log".into(),
        ),
        WorkoutPhase::ReadyToFinish => (
            "All sets complete".into(),
            "Finish to save the workout summary, then share or replay the exact local event log.".into(),
            "Finish, then share".into(),
        ),
        WorkoutPhase::Finished if state.projection.exported => (
            "Export shared".into(),
            "The shared text is still just a copy; this local event log remains the source.".into(),
            "Share again".into(),
        ),
        WorkoutPhase::Finished => (
            "Workout saved".into(),
            "Share the final event log, or replay it locally to prove recovery without hidden browser state.".into(),
            "Share final export".into(),
        ),
    };
    Workout {
        next_action: state.projection.next_action.clone(),
        primary_action: state.projection.primary_action.clone(),
        status: state.projection.progress.clone(),
        progress: state.projection.progress.clone(),
        recovery_status: state.recovery_text(),
        finish_title,
        finish_copy,
        share_action,
        event_log: state.event_log_text(),
        export_payload: if export.is_empty() {
            "Complete a set to create a replayable export.".into()
        } else {
            export
        },
        host_status: state.host_status.clone(),
    }
}

pub fn render(state: &WorkoutState) -> Html {
    ui::page(&view(state))
}

#[derive(Clone, Debug)]
#[hemx::form("change_weight")]
pub struct ChangeWeightInput {
    kg: String,
}

#[derive(Clone, Debug)]
#[hemx::form("correct_last_set")]
pub struct CorrectLastSetInput {
    kg: String,
}

#[derive(Clone, Debug)]
#[hemx::form("record_note")]
pub struct RecordNoteInput {
    text: String,
}

pub fn interactions(state: AppState) -> impl hemx_axum::DispatchRegistry {
    // req: codegen/002 req: examples/001
    hemx_axum::state_interactions(ui::BUILD_FINGERPRINT, state)
        .on_state(ui::workout::complete_set, complete_set)
        .on(ui::workout::change_weight, change_weight_form)
        .on(ui::workout::correct_last_set, correct_last_set_form)
        .on_state(ui::workout::skip_exercise, skip_exercise)
        .on(ui::workout::record_note, record_note_form)
        .on_state(ui::workout::undo_last_action, undo_last_action)
        .on_state(ui::workout::replay_export, replay_export)
        .on_state(ui::workout::export_log, export_log)
        .on_state(ui::workout::record_share_result, record_share_result)
        .on_state(ui::workout::record_share_denied, record_share_denied)
        .on_state(ui::workout::record_host_timeout, record_host_timeout)
        .on_state(ui::workout::replay_broken_export, replay_broken_export)
        .on_state(ui::workout::request_native_haptic, request_native_haptic)
        .on_state(
            ui::workout::record_native_haptic_ack,
            record_native_haptic_ack,
        )
}

fn effects(state: &WorkoutState, status: impl Into<String>) -> impl IntoEffect {
    // req: local/001 req: local/004
    let view = view(state);
    (
        ui::workout::next_action.text(&view.next_action),
        ui::workout::primary_action.text(&view.primary_action),
        ui::workout::status.text(status.into()),
        ui::workout::progress.text(&view.progress),
        ui::workout::recovery_status.text(&view.recovery_status),
        ui::workout::finish_title.text(&view.finish_title),
        ui::workout::finish_copy.text(&view.finish_copy),
        ui::workout::share_action.text(&view.share_action),
        ui::workout::event_log.text(&view.event_log),
        ui::workout::export_payload.text(&view.export_payload),
        ui::workout::host_status.text(&view.host_status),
    )
}

pub fn complete_set(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        let command = state.primary_command();
        let event = state.accept(command);
        if matches!(event, Some(WorkoutEvent::SetCompleted { .. })) {
            state.host_status =
                "Set saved locally; native haptic can acknowledge it without owning state.".into();
        }
        effects(
            state,
            event.map_or_else(
                || "Session is already saved; export is ready.".into(),
                |event| event.summary(),
            ),
        )
    })
}

pub fn change_weight(app: AppState, kg: f32) -> impl IntoEffect {
    app.update(|state| {
        let event = state.accept(WorkoutCommand::ChangeWeight { kg });
        effects(
            state,
            event.map_or_else(
                || "Enter a valid weight for the current or next exercise.".into(),
                |event| event.summary(),
            ),
        )
    })
}

pub fn correct_last_set(app: AppState, kg: f32) -> impl IntoEffect {
    app.update(|state| {
        let event = state.accept(WorkoutCommand::CorrectLastSet { kg });
        effects(
            state,
            event.map_or_else(
                || "Complete a set before correcting its recorded weight.".into(),
                |event| event.summary(),
            ),
        )
    })
}

pub fn skip_exercise(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        let event = state.accept(WorkoutCommand::SkipExercise);
        effects(
            state,
            event.map_or_else(
                || "No exercise available to skip.".into(),
                |event| event.summary(),
            ),
        )
    })
}

pub fn undo_last_action(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        let undone = state.undo_last_event();
        effects(
            state,
            undone.map_or_else(
                || "Nothing to undo yet; complete a set first.".into(),
                |summary| format!("Undid: {summary}"),
            ),
        )
    })
}

pub fn change_weight_form(app: AppState, Form(input): Form<ChangeWeightInput>) -> impl IntoEffect {
    app.update(|state| match input.kg.trim().parse::<f32>() {
        Ok(kg) if kg.is_finite() && kg >= 0.0 => {
            let event = state.accept(WorkoutCommand::ChangeWeight { kg });
            effects(
                state,
                event.map_or_else(
                    || "Enter a valid weight for the current or next exercise.".into(),
                    |event| event.summary(),
                ),
            )
        }
        _ => effects(
            state,
            String::from("Enter a valid non-negative weight; your session is unchanged."),
        ),
    })
}

pub fn correct_last_set_form(
    app: AppState,
    Form(input): Form<CorrectLastSetInput>,
) -> impl IntoEffect {
    app.update(|state| match input.kg.trim().parse::<f32>() {
        Ok(kg) if kg.is_finite() && kg >= 0.0 => {
            let event = state.accept(WorkoutCommand::CorrectLastSet { kg });
            effects(
                state,
                event.map_or_else(
                    || "Complete a set before correcting its recorded weight.".into(),
                    |event| event.summary(),
                ),
            )
        }
        _ => effects(
            state,
            String::from("Enter a valid corrected weight; your session is unchanged."),
        ),
    })
}

pub fn record_note_form(app: AppState, Form(input): Form<RecordNoteInput>) -> impl IntoEffect {
    record_note(app, input.text)
}

pub fn record_note(app: AppState, text: impl Into<String>) -> impl IntoEffect {
    app.update(|state| {
        let event = state.accept(WorkoutCommand::RecordNote { text: text.into() });
        effects(
            state,
            event.map_or_else(
                || "Ignored empty note; nothing changed.".into(),
                |event| event.summary(),
            ),
        )
    })
}

pub fn replay_export(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: local/001 req: local/003 req: local/004
        let export = state.export_event_log();
        match state.replay_export(&export) {
            Ok(count) => effects(state, format!("Replayed {count} exported workout events")),
            Err(error) => effects(
                state,
                format!("Replay failed: {error}. Current session is unchanged."),
            ),
        }
    })
}

pub fn replay_broken_export(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: local/001 req: local/003 req: local/004
        match state.replay_export("not-a-workout-export") {
            Ok(count) => effects(state, format!("Replayed {count} exported workout events")),
            Err(error) => effects(
                state,
                format!("Replay failed: {error}. Current session is unchanged."),
            ),
        }
    })
}

pub fn export_log(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: host/001 req: host/004 req: local/003
        if state.events.is_empty() {
            state.host_status = "Complete a set before opening the share sheet.".into();
            return effects(state, "Nothing to export yet");
        }
        let manifest = CapabilityManifest::new([CapabilityUse::new(
            Capability::Share,
            CapabilityShape::Request,
        )]);
        let call = HostCall::Share {
            id: HostCallId::new("workout-export"),
            payload: HostShareData::text(state.export_event_log()),
        };
        state.host_status = match manifest.validate_call(&browser_pwa_host_profile(), &call) {
            Ok(()) => "Share sheet requested; your local event log remains the source.".into(),
            Err(error) => format!("Share unavailable: {error}. Export text stays below."),
        };
        effects(state, "Share export prepared")
    })
}

pub fn record_share_result(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: host/002 req: host/005 req: local/003
        apply_host_event(
            state,
            HostEvent::ShareCompleted {
                id: HostCallId::new("workout-export"),
                completed: true,
            },
        );
        effects(state, "Share result returned through app code")
    })
}

pub fn record_share_denied(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: host/002 req: host/005 req: local/003
        apply_host_event(
            state,
            HostEvent::Failed(
                HostFailure::new(HostFailureKind::PermissionDenied, "share permission denied")
                    .with_capability(Capability::Share),
            ),
        );
        effects(state, "Share permission denial returned through app code")
    })
}

pub fn record_host_timeout(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: host/002 req: host/005 req: local/003
        apply_host_event(
            state,
            HostEvent::Failed(
                HostFailure::new(HostFailureKind::Timeout, "share timed out")
                    .with_id(HostCallId::new("workout-export"))
                    .with_capability(Capability::Share),
            ),
        );
        effects(state, "Host timeout returned through app code")
    })
}

pub fn request_native_haptic(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: host/001 req: host/004
        let manifest = CapabilityManifest::new([CapabilityUse::new(
            Capability::Haptics,
            CapabilityShape::Fire,
        )]);
        let call = HostCall::Haptic {
            id: HostCallId::new("workout-set-haptic"),
            pattern: HapticPattern::Success,
        };
        state.host_status = match manifest.validate_call(
            &native_shell_host_profile("ios-android-webview-workout"),
            &call,
        ) {
            Ok(()) => "Native-shell haptic requested for the saved set.".into(),
            Err(error) => format!("Native haptic unavailable: {error}"),
        };
        effects(state, "Native-shell host call checked against manifest")
    })
}

pub fn record_native_haptic_ack(app: AppState) -> impl IntoEffect {
    app.update(|state| {
        // req: host/002 req: host/005
        apply_host_event(
            state,
            HostEvent::Acknowledged {
                id: HostCallId::new("workout-set-haptic"),
            },
        );
        effects(state, "Native-shell host result accepted by app code")
    })
}

fn host_failure_label(kind: HostFailureKind) -> &'static str {
    match kind {
        HostFailureKind::PermissionDenied => "permission denied",
        HostFailureKind::Timeout => "timeout",
        HostFailureKind::Unavailable => "unavailable",
        HostFailureKind::Error => "error",
    }
}

fn apply_host_event(state: &mut WorkoutState, event: HostEvent) {
    match event {
        HostEvent::ShareCompleted {
            completed: true, ..
        } => {
            state.projection.exported = true;
            state.host_status = "Shared. The replayable event log remains local truth.".into();
        }
        HostEvent::ShareCompleted {
            completed: false, ..
        } => {
            state.host_status =
                "Share cancelled; local event log unchanged. Try Share export when ready.".into();
        }
        HostEvent::Failed(failure)
            if failure.kind == HostFailureKind::PermissionDenied
                && failure.capability == Some(Capability::Share) =>
        {
            state.host_status =
                "Share permission denied. Local export text is still ready; try again or copy it."
                    .into();
        }
        HostEvent::Failed(failure) => {
            state.host_status = format!(
                "Host {}: {}. Keep the local export below and try Share export again.",
                host_failure_label(failure.kind),
                failure.message
            );
        }
        HostEvent::Acknowledged { id } if id.0 == "workout-set-haptic" => {
            state.host_status =
                "Native haptic acknowledged; workout state stayed app-owned.".into();
        }
        _ => {
            state.host_status = "Host event ignored by app policy.".into();
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use hemx::advanced::{Effect, Payload};
    use hemx_test::run;

    fn contains_payload_text(effects: &hemx_test::EffectInspector, needle: &str) -> bool {
        effects.batch().ops.iter().any(|op| {
            matches!(op, Effect::Put { payload: Payload::Text(text), .. } if text.contains(needle))
        })
    }

    #[test]
    fn local_command_projects_before_ui_effects() {
        // req: local/001 req: local/004
        let app = AppState::demo();
        let effects = run(|()| complete_set(app.clone()), ());

        assert_eq!(
            app.with_workout(|state| (
                state.commands.len(),
                state.events.len(),
                state.projection.completed_sets_for_current,
                state.projection.phase.clone(),
            )),
            (1, 1, 1, WorkoutPhase::Resting)
        );
        assert!(contains_payload_text(
            &effects,
            "completed Goblet squat set 1"
        ));
        assert!(contains_payload_text(&effects, "Rest 90s"));
        assert!(contains_payload_text(&effects, "Start Goblet squat set 2"));
        assert_eq!(
            app.with_workout(|state| (state.commands.len(), state.events.len())),
            (1, 1)
        );
    }

    #[test]
    fn primary_action_moves_from_rest_to_next_set_and_finish() {
        // req: examples/001 req: local/001 req: local/004
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());
        let rest = run(|()| complete_set(app.clone()), ());
        assert!(contains_payload_text(&rest, "started Goblet squat set 2"));
        assert_eq!(
            app.with_workout(|state| state.projection.phase.clone()),
            WorkoutPhase::Ready
        );

        for _ in 0..7 {
            run(|()| complete_set(app.clone()), ());
        }
        assert_eq!(
            app.with_workout(|state| state.projection.phase.clone()),
            WorkoutPhase::ReadyToFinish
        );
        let finished = run(|()| complete_set(app.clone()), ());
        assert!(contains_payload_text(
            &finished,
            "finished workout: 5/5 sets complete"
        ));
        assert!(contains_payload_text(&finished, "Workout saved"));
        assert!(contains_payload_text(&finished, "Share final export"));
        assert_eq!(
            app.with_workout(|state| state.projection.phase.clone()),
            WorkoutPhase::Finished
        );
    }

    #[test]
    fn double_primary_action_recovers_through_undo() {
        // req: examples/001 req: local/001 req: local/004
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());
        let double_action = run(|()| complete_set(app.clone()), ());
        assert!(contains_payload_text(
            &double_action,
            "started Goblet squat set 2"
        ));
        assert_eq!(
            app.with_workout(|state| (state.events.len(), state.projection.phase.clone())),
            (2, WorkoutPhase::Ready)
        );

        let undone = run(|()| undo_last_action(app.clone()), ());
        assert!(contains_payload_text(
            &undone,
            "Undid: started Goblet squat set 2"
        ));
        assert!(contains_payload_text(&undone, "Rest 90s"));
        assert_eq!(
            app.with_workout(|state| (state.events.len(), state.projection.phase.clone())),
            (1, WorkoutPhase::Resting)
        );
    }

    #[test]
    fn correct_last_set_is_replayable_and_undoable() {
        // req: examples/001 req: local/001 req: local/003 req: local/004
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());

        let corrected = run(|()| correct_last_set(app.clone(), 26.0), ());
        assert!(contains_payload_text(
            &corrected,
            "corrected Goblet squat set 1 to 26 kg"
        ));
        assert_eq!(
            app.with_workout(|state| (state.events.len(), state.plan[0].kg)),
            (2, 26.0)
        );
        let export = app.with_workout(WorkoutState::export_event_log);
        assert!(export.contains("set_edited\tGoblet squat\t1\t26"));

        let replay = run(|()| replay_export(app.clone()), ());
        assert!(contains_payload_text(
            &replay,
            "Replayed 2 exported workout events"
        ));
        assert_eq!(app.with_workout(|state| state.plan[0].kg), 26.0);

        let undone = run(|()| undo_last_action(app.clone()), ());
        assert!(contains_payload_text(
            &undone,
            "Undid: corrected Goblet squat set 1 to 26 kg"
        ));
        assert_eq!(app.with_workout(|state| state.plan[0].kg), 24.0);
    }

    #[test]
    fn skipped_exercise_recovers_through_undo() {
        // req: examples/001 req: local/001 req: local/004
        let app = AppState::demo();

        let skipped = run(|()| skip_exercise(app.clone()), ());
        assert!(contains_payload_text(&skipped, "skipped Goblet squat"));
        assert!(contains_payload_text(&skipped, "Next: Push-up set 1/2"));
        assert_eq!(
            app.with_workout(|state| (
                state.events.len(),
                state.projection.current_exercise,
                state.projection.phase.clone(),
            )),
            (1, 1, WorkoutPhase::Ready)
        );

        let undone = run(|()| undo_last_action(app.clone()), ());
        assert!(contains_payload_text(
            &undone,
            "Undid: skipped Goblet squat"
        ));
        assert!(contains_payload_text(&undone, "Next: Goblet squat set 1/3"));
        assert_eq!(
            app.with_workout(|state| (
                state.events.len(),
                state.projection.current_exercise,
                state.projection.phase.clone(),
            )),
            (0, 0, WorkoutPhase::Ready)
        );
    }

    #[test]
    fn undo_recovers_last_session_action() {
        // req: examples/001 req: local/001 req: local/004
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());
        let undone = run(|()| undo_last_action(app.clone()), ());

        assert!(contains_payload_text(
            &undone,
            "Undid: completed Goblet squat set 1"
        ));
        assert_eq!(
            app.with_workout(|state| (
                state.events.len(),
                state.projection.completed_sets_for_current,
                state.projection.phase.clone(),
            )),
            (0, 0, WorkoutPhase::Ready)
        );
    }

    #[test]
    fn invalid_weight_and_replay_failure_keep_session_recoverable() {
        // req: examples/001 req: local/001 req: local/003 req: local/004
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());

        let invalid = run(
            |input| change_weight_form(app.clone(), Form(input)),
            ChangeWeightInput { kg: "oops".into() },
        );
        assert!(contains_payload_text(&invalid, "valid non-negative weight"));
        assert_eq!(
            app.with_workout(|state| (state.events.len(), state.projection.phase.clone())),
            (1, WorkoutPhase::Resting)
        );

        let replay = run(|()| replay_broken_export(app.clone()), ());
        assert!(contains_payload_text(&replay, "Replay failed: line 1"));
        assert!(contains_payload_text(
            &replay,
            "Current session is unchanged"
        ));
        assert_eq!(app.with_workout(|state| state.events.len()), 1);
    }

    #[test]
    fn export_payload_replays_into_projection_before_ui_effects() {
        // req: local/001 req: local/003 req: local/004
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());
        run(|()| complete_set(app.clone()), ());
        run(|()| change_weight(app.clone(), 28.0), ());
        let export = app.with_workout(WorkoutState::export_event_log);
        assert!(export.contains("set_completed\tGoblet squat\t1\t8\t24"));
        assert!(export.contains("rest_finished\tGoblet squat\t2"));
        assert!(export.contains("weight_changed\tGoblet squat\t28"));

        let replay = run(|()| replay_export(app.clone()), ());
        assert!(contains_payload_text(
            &replay,
            "Replayed 3 exported workout events"
        ));
        assert_eq!(
            app.with_workout(|state| {
                (
                    state.events.len(),
                    state.projection.completed_sets_for_current,
                    state.plan[0].kg,
                    state.projection.phase.clone(),
                )
            }),
            (3, 1, 28.0, WorkoutPhase::Ready)
        );
    }

    #[test]
    fn host_export_result_returns_through_app_code() {
        // req: host/001 req: host/002 req: host/005 req: local/003
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());

        let export = run(|()| export_log(app.clone()), ());
        assert!(contains_payload_text(&export, "Share export prepared"));
        assert!(contains_payload_text(&export, "Share sheet requested"));

        let shared = run(|()| record_share_result(app.clone()), ());
        assert!(app.with_workout(|state| state.projection.exported));
        assert!(contains_payload_text(
            &shared,
            "Share result returned through app code"
        ));
        assert!(contains_payload_text(
            &shared,
            "replayable event log remains local truth"
        ));
    }

    #[test]
    fn host_failure_results_keep_local_export_recoverable() {
        // req: host/002 req: host/005 req: local/003
        let app = AppState::demo();
        run(|()| complete_set(app.clone()), ());

        let denied = run(|()| record_share_denied(app.clone()), ());
        assert!(contains_payload_text(&denied, "Share permission denial"));
        assert!(contains_payload_text(
            &denied,
            "Local export text is still ready"
        ));
        assert!(!app.with_workout(|state| state.projection.exported));

        let timeout = run(|()| record_host_timeout(app.clone()), ());
        assert!(contains_payload_text(&timeout, "Host timeout"));
        assert!(contains_payload_text(
            &timeout,
            "Keep the local export below"
        ));
        assert_eq!(app.with_workout(|state| state.events.len()), 1);
    }

    #[test]
    fn native_shell_haptic_result_returns_through_app_code() {
        // req: host/001 req: host/002 req: host/005
        let app = AppState::demo();

        let request = run(|()| request_native_haptic(app.clone()), ());
        assert!(contains_payload_text(
            &request,
            "Native-shell host call checked against manifest"
        ));
        assert!(contains_payload_text(
            &request,
            "Native-shell haptic requested"
        ));

        let ack = run(|()| record_native_haptic_ack(app.clone()), ());
        assert!(contains_payload_text(
            &ack,
            "Native-shell host result accepted by app code"
        ));
        assert!(contains_payload_text(
            &ack,
            "workout state stayed app-owned"
        ));
    }

    #[test]
    fn rendered_page_has_phone_first_controls_without_user_js() {
        // req: examples/001 req: examples/005
        let html = render(&WorkoutState::demo()).to_string();
        assert!(html.contains("Now-first Workout Copilot"));
        assert!(html.contains("Complete set"));
        assert!(html.contains("Finish unlocks as you train"));
        assert!(html.contains("Export after first set"));
        assert!(html.contains("Undo last action"));
        assert!(html.contains("Correct last set"));
        assert!(html.contains("Host proof panel"));
        assert!(html.contains("Simulate share denied"));
        assert!(html.contains("Simulate replay failure"));
        assert!(!html.contains(&format!("<{}", "script")));
        assert!(!html.contains("querySelector"));
    }
}