//! Discloser Widget - Expandable/collapsible container
//!
//! A disclosure triangle that reveals content when expanded.
//! Similar to HTML details/summary or macOS disclosure triangles.

const std = @import("std");
const Context = @import("../core/context.zig").Context;
const Command = @import("../core/command.zig");
const Layout = @import("../core/layout.zig");
const Style = @import("../core/style.zig");
const Input = @import("../core/input.zig");

/// Discloser icon style
pub const IconStyle = enum {
    /// Triangle arrow (default)
    arrow,
    /// Plus/minus signs
    plus_minus,
    /// Chevron
    chevron,
};

/// Discloser state
pub const State = struct {
    /// Is content expanded
    is_expanded: bool = false,
    /// Animation progress (0 = collapsed, 1 = expanded)
    animation_progress: f32 = 0,

    pub fn init(initially_expanded: bool) State {
        return .{
            .is_expanded = initially_expanded,
            .animation_progress = if (initially_expanded) 1.0 else 0.0,
        };
    }

    pub fn toggle(self: *State) void {
        self.is_expanded = !self.is_expanded;
    }

    pub fn expand(self: *State) void {
        self.is_expanded = true;
    }

    pub fn collapse(self: *State) void {
        self.is_expanded = false;
    }
};

/// Discloser configuration
pub const Config = struct {
    /// Header label
    label: []const u8,
    /// Icon style
    icon_style: IconStyle = .arrow,
    /// Header height
    header_height: u16 = 32,
    /// Content height (when expanded)
    content_height: u16 = 100,
    /// Indentation for content
    indent: u16 = 24,
    /// Animation speed
    animation_speed: f32 = 0.15,
    /// Show border around content
    show_border: bool = false,
};

/// Discloser colors
pub const Colors = struct {
    /// Header background
    header_bg: Style.Color = Style.Color.rgba(0, 0, 0, 0),
    /// Header background (hover)
    header_hover: Style.Color = Style.Color.rgba(255, 255, 255, 10),
    /// Header text
    header_text: Style.Color = Style.Color.rgb(220, 220, 220),
    /// Icon color
    icon: Style.Color = Style.Color.rgb(150, 150, 150),
    /// Content background
    content_bg: Style.Color = Style.Color.rgba(0, 0, 0, 0),
    /// Border
    border: Style.Color = Style.Color.rgb(60, 60, 60),

    pub fn fromTheme(theme: Style.Theme) Colors {
        return .{
            .header_bg = Style.Color.transparent,
            .header_hover = theme.foreground.withAlpha(10),
            .header_text = theme.foreground,
            .icon = theme.foreground.darken(30),
            .content_bg = Style.Color.transparent,
            .border = theme.border,
        };
    }
};

/// Discloser result
pub const Result = struct {
    /// Header was clicked
    clicked: bool,
    /// Is currently expanded
    expanded: bool,
    /// Content area (where to draw child content)
    content_rect: Layout.Rect,
    /// Total bounds used
    bounds: Layout.Rect,
    /// Should draw content this frame
    should_draw_content: bool,
};

/// Simple discloser
pub fn discloser(ctx: *Context, state: *State, label_text: []const u8) Result {
    return discloserEx(ctx, state, .{ .label = label_text }, .{});
}

/// Discloser with configuration
pub fn discloserEx(ctx: *Context, state: *State, config: Config, colors: Colors) Result {
    const header_rect = ctx.layout.nextRect();
    return discloserRect(ctx, header_rect, state, config, colors);
}

/// Discloser in specific rectangle
pub fn discloserRect(
    ctx: *Context,
    header_rect: Layout.Rect,
    state: *State,
    config: Config,
    colors: Colors,
) Result {
    if (header_rect.isEmpty()) {
        return .{
            .clicked = false,
            .expanded = state.is_expanded,
            .content_rect = Layout.Rect{ .x = 0, .y = 0, .w = 0, .h = 0 },
            .bounds = header_rect,
            .should_draw_content = false,
        };
    }

    // Update animation
    const target: f32 = if (state.is_expanded) 1.0 else 0.0;
    if (state.animation_progress < target) {
        state.animation_progress = @min(target, state.animation_progress + config.animation_speed);
    } else if (state.animation_progress > target) {
        state.animation_progress = @max(target, state.animation_progress - config.animation_speed);
    }

    // Mouse interaction
    const mouse = ctx.input.mousePos();
    const hovered = header_rect.contains(mouse.x, mouse.y);
    const clicked = hovered and ctx.input.mouseReleased(.left);

    if (clicked) {
        state.toggle();
    }

    // Draw header background
    if (hovered) {
        ctx.pushCommand(Command.rect(header_rect.x, header_rect.y, header_rect.w, header_rect.h, colors.header_hover));
    }

    // Draw icon
    const icon_x = header_rect.x + 4;
    const icon_y = header_rect.y + @as(i32, @intCast((header_rect.h - 16) / 2));
    drawIcon(ctx, icon_x, icon_y, config.icon_style, state.animation_progress, colors.icon);

    // Draw label
    const label_x = header_rect.x + 24;
    const label_y = header_rect.y + @as(i32, @intCast((header_rect.h - 8) / 2));
    ctx.pushCommand(Command.text(label_x, label_y, config.label, colors.header_text));

    // Calculate content area
    const content_height = @as(u32, @intFromFloat(@as(f32, @floatFromInt(config.content_height)) * state.animation_progress));
    const content_rect = Layout.Rect{
        .x = header_rect.x + @as(i32, @intCast(config.indent)),
        .y = header_rect.y + @as(i32, @intCast(config.header_height)),
        .w = header_rect.w -| config.indent,
        .h = content_height,
    };

    // Draw content background and clip
    if (state.animation_progress > 0.01) {
        if (colors.content_bg.a > 0) {
            ctx.pushCommand(Command.rect(content_rect.x, content_rect.y, content_rect.w, content_rect.h, colors.content_bg));
        }

        if (config.show_border and state.animation_progress > 0.5) {
            ctx.pushCommand(Command.rectOutline(
                content_rect.x - 1,
                content_rect.y,
                content_rect.w + 2,
                content_rect.h,
                colors.border,
            ));
        }

        // Push clip for content
        ctx.pushCommand(Command.clip(content_rect.x, content_rect.y, content_rect.w, content_rect.h));
    }

    const total_height = config.header_height + content_height;
    const total_bounds = Layout.Rect{
        .x = header_rect.x,
        .y = header_rect.y,
        .w = header_rect.w,
        .h = total_height,
    };

    return .{
        .clicked = clicked,
        .expanded = state.is_expanded,
        .content_rect = content_rect,
        .bounds = total_bounds,
        .should_draw_content = state.animation_progress > 0.01,
    };
}

/// End discloser content (pop clip)
pub fn discloserEnd(ctx: *Context, result: Result) void {
    if (result.should_draw_content) {
        ctx.pushCommand(.clip_end);
    }
}

fn drawIcon(ctx: *Context, x: i32, y: i32, style: IconStyle, progress: f32, color: Style.Color) void {
    const size: i32 = 12;
    const half = size / 2;

    switch (style) {
        .arrow => {
            // Rotating triangle
            if (progress < 0.5) {
                // Right-pointing arrow
                ctx.pushCommand(Command.line(x + 2, y + 2, x + size - 2, y + half, color));
                ctx.pushCommand(Command.line(x + size - 2, y + half, x + 2, y + size - 2, color));
            } else {
                // Down-pointing arrow
                ctx.pushCommand(Command.line(x + 2, y + 2, x + half, y + size - 2, color));
                ctx.pushCommand(Command.line(x + half, y + size - 2, x + size - 2, y + 2, color));
            }
        },
        .plus_minus => {
            // Horizontal line (always)
            ctx.pushCommand(Command.line(x + 2, y + half, x + size - 2, y + half, color));
            // Vertical line (when collapsed)
            if (progress < 0.5) {
                ctx.pushCommand(Command.line(x + half, y + 2, x + half, y + size - 2, color));
            }
        },
        .chevron => {
            if (progress < 0.5) {
                // Right chevron
                ctx.pushCommand(Command.line(x + 3, y + 2, x + size - 3, y + half, color));
                ctx.pushCommand(Command.line(x + size - 3, y + half, x + 3, y + size - 2, color));
            } else {
                // Down chevron
                ctx.pushCommand(Command.line(x + 2, y + 3, x + half, y + size - 3, color));
                ctx.pushCommand(Command.line(x + half, y + size - 3, x + size - 2, y + 3, color));
            }
        },
    }
}

// =============================================================================
// Tests
// =============================================================================

test "discloser state" {
    var state = State.init(false);
    try std.testing.expect(!state.is_expanded);

    state.toggle();
    try std.testing.expect(state.is_expanded);

    state.collapse();
    try std.testing.expect(!state.is_expanded);

    state.expand();
    try std.testing.expect(state.is_expanded);
}

test "discloser generates commands" {
    var ctx = try Context.init(std.testing.allocator, 800, 600);
    defer ctx.deinit();

    var state = State.init(false);

    ctx.beginFrame();
    ctx.layout.row_height = 32;

    const result = discloser(&ctx, &state, "Section");

    try std.testing.expect(ctx.commands.items.len >= 2);
    try std.testing.expect(!result.expanded);

    ctx.endFrame();
}

test "discloser expanded shows content" {
    var ctx = try Context.init(std.testing.allocator, 800, 600);
    defer ctx.deinit();

    var state = State.init(true);
    state.animation_progress = 1.0;

    ctx.beginFrame();
    ctx.layout.row_height = 32;

    const result = discloserEx(&ctx, &state, .{
        .label = "Section",
        .content_height = 100,
    }, .{});

    try std.testing.expect(result.expanded);
    try std.testing.expect(result.should_draw_content);
    try std.testing.expect(result.content_rect.h > 0);

    discloserEnd(&ctx, result);
    ctx.endFrame();
}

test "discloser icon styles" {
    var ctx = try Context.init(std.testing.allocator, 800, 600);
    defer ctx.deinit();

    const styles = [_]IconStyle{ .arrow, .plus_minus, .chevron };

    for (styles) |style| {
        var state = State.init(false);

        ctx.beginFrame();
        ctx.layout.row_height = 32;

        _ = discloserEx(&ctx, &state, .{
            .label = "Test",
            .icon_style = style,
        }, .{});

        try std.testing.expect(ctx.commands.items.len >= 2);

        ctx.endFrame();
    }
}