mim/src/pi_bridge.zig

const std = @import("std");

// Foreground Pi/local assistant bridge over compact context.
// req: session/002, session/004, governance/002, governance/003, testing/001, testing/002

test {
    _ = rowsAlloc;
}

pub const Error = error{
    InvalidCommand,
    InvalidContext,
};

pub fn rowsAlloc(allocator: std.mem.Allocator, io: std.Io, argv: []const []const u8, context: []const u8) ![][]const u8 {
    try validateArgv(argv);
    try validateContext(context);
    const full_argv = try allocator.alloc([]const u8, argv.len + 1);
    defer allocator.free(full_argv);
    @memcpy(full_argv[0..argv.len], argv);
    full_argv[argv.len] = context;

    var rows = std.ArrayList([]const u8).empty;
    errdefer {
        for (rows.items) |row| allocator.free(row);
        rows.deinit(allocator);
    }
    const preview = try commandPreviewAlloc(allocator, argv);
    defer allocator.free(preview);
    try rows.append(allocator, try std.fmt.allocPrint(allocator, "pi:spawned:{s}", .{preview}));
    try rows.append(allocator, try std.fmt.allocPrint(allocator, "pi:context:bytes_{d}", .{context.len}));

    const result = std.process.run(allocator, io, .{
        .argv = full_argv,
        .stdout_limit = .limited(128 * 1024),
        .stderr_limit = .limited(64 * 1024),
    }) catch |err| {
        try rows.append(allocator, try std.fmt.allocPrint(allocator, "pi:status:spawn_error_{s}", .{@errorName(err)}));
        return rows.toOwnedSlice(allocator);
    };
    defer allocator.free(result.stdout);
    defer allocator.free(result.stderr);

    try appendTermRow(allocator, &rows, result.term);
    try appendOutputRows(allocator, &rows, "stdout", result.stdout);
    try appendOutputRows(allocator, &rows, "stderr", result.stderr);
    if (rows.items.len == 3) try rows.append(allocator, try allocator.dupe(u8, "pi:output_empty"));
    return rows.toOwnedSlice(allocator);
}

fn validateArgv(argv: []const []const u8) !void {
    if (argv.len == 0) return Error.InvalidCommand;
    for (argv) |arg| {
        if (arg.len == 0 or !std.unicode.utf8ValidateSlice(arg)) return Error.InvalidCommand;
        for (arg) |byte| if (byte == 0 or byte == '\n' or byte == '\r') return Error.InvalidCommand;
    }
}

fn validateContext(context: []const u8) !void {
    if (context.len == 0 or !std.unicode.utf8ValidateSlice(context)) return Error.InvalidContext;
    for (context) |byte| if (byte == 0) return Error.InvalidContext;
}

fn appendTermRow(allocator: std.mem.Allocator, rows: *std.ArrayList([]const u8), term: std.process.Child.Term) !void {
    const row = switch (term) {
        .exited => |code| try std.fmt.allocPrint(allocator, "pi:status:exit_{d}", .{code}),
        .signal => |sig| try std.fmt.allocPrint(allocator, "pi:status:signal_{d}", .{@intFromEnum(sig)}),
        .stopped => |sig| try std.fmt.allocPrint(allocator, "pi:status:stopped_{d}", .{@intFromEnum(sig)}),
        .unknown => |code| try std.fmt.allocPrint(allocator, "pi:status:unknown_{d}", .{code}),
    };
    try rows.append(allocator, row);
}

fn appendOutputRows(allocator: std.mem.Allocator, rows: *std.ArrayList([]const u8), prefix: []const u8, output: []const u8) !void {
    var lines = std.mem.splitScalar(u8, output, '\n');
    while (lines.next()) |raw_line| {
        const trimmed = std.mem.trim(u8, raw_line, "\r");
        if (trimmed.len == 0) continue;
        const sanitized = try sanitizeAlloc(allocator, trimmed, 120);
        defer allocator.free(sanitized);
        try rows.append(allocator, try std.fmt.allocPrint(allocator, "{s}:{s}", .{ prefix, sanitized }));
    }
}

fn commandPreviewAlloc(allocator: std.mem.Allocator, argv: []const []const u8) ![]u8 {
    var out = std.ArrayList(u8).empty;
    errdefer out.deinit(allocator);
    for (argv, 0..) |arg, index| {
        if (index != 0) try out.append(allocator, '_');
        const clean = try sanitizeAlloc(allocator, arg, 40);
        defer allocator.free(clean);
        try out.appendSlice(allocator, clean);
        if (out.items.len >= 120) break;
    }
    return out.toOwnedSlice(allocator);
}

fn sanitizeAlloc(allocator: std.mem.Allocator, value: []const u8, max_len: usize) ![]u8 {
    var out = std.ArrayList(u8).empty;
    errdefer out.deinit(allocator);
    var i: usize = 0;
    while (i < value.len and out.items.len < max_len) {
        const len = std.unicode.utf8ByteSequenceLength(value[i]) catch 1;
        const end = @min(value.len, i + len);
        const slice = value[i..end];
        if (slice.len == 1 and (slice[0] <= 0x20 or slice[0] == '|')) {
            try out.append(allocator, '_');
        } else {
            try out.appendSlice(allocator, slice);
        }
        i = end;
    }
    if (i < value.len) try out.appendSlice(allocator, "...");
    if (out.items.len == 0) try out.append(allocator, '_');
    return out.toOwnedSlice(allocator);
}

fn freeRows(allocator: std.mem.Allocator, rows: []const []const u8) void {
    for (rows) |row| allocator.free(row);
    allocator.free(rows);
}

test "regular: fake pi command receives context and emits output rows" {
    const context = "context:v1\ntask=fix_bug\n";
    const rows = try rowsAlloc(std.testing.allocator, std.testing.io, &.{ "sh", "-c", "case \"$1\" in *context:v1*) echo pi_ok;; *) echo missing; exit 2;; esac", "fake-pi" }, context);
    defer freeRows(std.testing.allocator, rows);
    try std.testing.expectEqualStrings("pi:status:exit_0", rows[2]);
    try std.testing.expectEqualStrings("stdout:pi_ok", rows[3]);
}

test "adversarial: missing pi command and invalid input are explicit" {
    try std.testing.expectError(Error.InvalidCommand, rowsAlloc(std.testing.allocator, std.testing.io, &.{}, "context:v1\n"));
    try std.testing.expectError(Error.InvalidContext, rowsAlloc(std.testing.allocator, std.testing.io, &.{"true"}, ""));
    const rows = try rowsAlloc(std.testing.allocator, std.testing.io, &.{"definitely-not-a-mim-pi"}, "context:v1\n");
    defer freeRows(std.testing.allocator, rows);
    try std.testing.expect(std.mem.startsWith(u8, rows[2], "pi:status:spawn_error_"));
}