//! NavDrawer Widget - Navigation drawer
//!
//! A side panel for app navigation with items and optional header.
//! Can be static or modal (with scrim overlay).

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");
const icon_module = @import("icon.zig");

/// Navigation item
pub const NavItem = struct {
    /// Item ID for selection tracking
    id: u32,
    /// Item label
    label: []const u8,
    /// Optional icon
    icon: ?icon_module.IconType = null,
    /// Badge text (e.g., notification count)
    badge: ?[]const u8 = null,
    /// Disabled state
    disabled: bool = false,
    /// Divider after this item
    divider_after: bool = false,
};

/// Drawer header
pub const Header = struct {
    /// Header title
    title: []const u8,
    /// Subtitle
    subtitle: ?[]const u8 = null,
    /// Header height
    height: u16 = 160,
};

/// NavDrawer state
pub const State = struct {
    /// Currently selected item ID
    selected_id: ?u32 = null,
    /// Hovered item ID
    hovered_id: ?u32 = null,
    /// Is drawer open (for modal drawer)
    is_open: bool = false,
    /// Animation progress (0 = closed, 1 = open)
    animation_progress: f32 = 0,

    pub fn init() State {
        return .{};
    }

    pub fn open(self: *State) void {
        self.is_open = true;
    }

    pub fn close(self: *State) void {
        self.is_open = false;
    }

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

/// NavDrawer configuration
pub const Config = struct {
    /// Drawer width
    width: u16 = 280,
    /// Navigation items
    items: []const NavItem = &.{},
    /// Optional header
    header: ?Header = null,
    /// Item height
    item_height: u16 = 48,
    /// Show selection indicator
    show_indicator: bool = true,
};

/// NavDrawer colors
pub const Colors = struct {
    /// Drawer background
    background: Style.Color = Style.Color.rgb(30, 30, 30),
    /// Header background
    header_bg: Style.Color = Style.Color.rgb(45, 45, 45),
    /// Header title
    header_title: Style.Color = Style.Color.rgb(255, 255, 255),
    /// Header subtitle
    header_subtitle: Style.Color = Style.Color.rgb(180, 180, 180),
    /// Item text
    item_text: Style.Color = Style.Color.rgb(220, 220, 220),
    /// Item text (selected)
    item_selected: Style.Color = Style.Color.rgb(66, 133, 244),
    /// Item background (hover)
    item_hover: Style.Color = Style.Color.rgba(255, 255, 255, 15),
    /// Item background (selected)
    item_selected_bg: Style.Color = Style.Color.rgba(66, 133, 244, 30),
    /// Selection indicator
    indicator: Style.Color = Style.Color.rgb(66, 133, 244),
    /// Icon color
    icon: Style.Color = Style.Color.rgb(180, 180, 180),
    /// Icon color (selected)
    icon_selected: Style.Color = Style.Color.rgb(66, 133, 244),
    /// Divider
    divider_color: Style.Color = Style.Color.rgb(60, 60, 60),
    /// Badge background
    badge_bg: Style.Color = Style.Color.rgb(244, 67, 54),
    /// Badge text
    badge_text: Style.Color = Style.Color.white,
    /// Scrim (for modal)
    scrim: Style.Color = Style.Color.rgba(0, 0, 0, 120),

    pub fn fromTheme(theme: Style.Theme) Colors {
        return .{
            .background = theme.panel_bg,
            .header_bg = theme.panel_bg.lighten(10),
            .header_title = theme.foreground,
            .header_subtitle = theme.foreground.darken(20),
            .item_text = theme.foreground,
            .item_selected = theme.primary,
            .item_hover = theme.foreground.withAlpha(15),
            .item_selected_bg = theme.primary.withAlpha(30),
            .indicator = theme.primary,
            .icon = theme.foreground.darken(20),
            .icon_selected = theme.primary,
            .divider_color = theme.border,
            .badge_bg = theme.danger,
            .badge_text = Style.Color.white,
            .scrim = Style.Color.rgba(0, 0, 0, 120),
        };
    }
};

/// NavDrawer result
pub const Result = struct {
    /// Item that was clicked (ID)
    clicked: ?u32,
    /// Drawer bounds
    bounds: Layout.Rect,
    /// Content area (to the right of drawer)
    content_rect: Layout.Rect,
};

/// Static navigation drawer
pub fn navDrawer(ctx: *Context, state: *State, config: Config, colors: Colors) Result {
    const bounds = Layout.Rect{
        .x = 0,
        .y = 0,
        .w = config.width,
        .h = ctx.layout.area.h,
    };

    return navDrawerRect(ctx, bounds, state, config, colors);
}

/// Navigation drawer in specific rectangle
pub fn navDrawerRect(
    ctx: *Context,
    bounds: Layout.Rect,
    state: *State,
    config: Config,
    colors: Colors,
) Result {
    if (bounds.isEmpty()) {
        return .{
            .clicked = null,
            .bounds = bounds,
            .content_rect = Layout.Rect{ .x = 0, .y = 0, .w = 0, .h = 0 },
        };
    }

    var clicked: ?u32 = null;

    // Draw background
    ctx.pushCommand(Command.rect(bounds.x, bounds.y, bounds.w, bounds.h, colors.background));

    var current_y = bounds.y;

    // Draw header
    if (config.header) |header| {
        ctx.pushCommand(Command.rect(bounds.x, current_y, bounds.w, header.height, colors.header_bg));

        // Title
        const title_x = bounds.x + 16;
        const title_y = current_y + @as(i32, @intCast(header.height)) - 40;
        ctx.pushCommand(Command.text(title_x, title_y, header.title, colors.header_title));

        // Subtitle
        if (header.subtitle) |subtitle| {
            ctx.pushCommand(Command.text(title_x, title_y + 16, subtitle, colors.header_subtitle));
        }

        current_y += @as(i32, @intCast(header.height));
    }

    // Reset hovered
    state.hovered_id = null;

    // Draw items
    const mouse = ctx.input.mousePos();

    for (config.items) |item| {
        const item_bounds = Layout.Rect{
            .x = bounds.x,
            .y = current_y,
            .w = bounds.w,
            .h = config.item_height,
        };

        const is_selected = state.selected_id == item.id;
        const is_hovered = item_bounds.contains(mouse.x, mouse.y) and !item.disabled;

        if (is_hovered) {
            state.hovered_id = item.id;
        }

        // Handle click
        if (is_hovered and ctx.input.mouseReleased(.left)) {
            state.selected_id = item.id;
            clicked = item.id;
        }

        // Draw item background
        if (is_selected) {
            ctx.pushCommand(Command.rect(item_bounds.x, item_bounds.y, item_bounds.w, item_bounds.h, colors.item_selected_bg));

            // Selection indicator
            if (config.show_indicator) {
                ctx.pushCommand(Command.rect(item_bounds.x, item_bounds.y, 4, item_bounds.h, colors.indicator));
            }
        } else if (is_hovered) {
            ctx.pushCommand(Command.rect(item_bounds.x, item_bounds.y, item_bounds.w, item_bounds.h, colors.item_hover));
        }

        // Draw icon
        var text_x = bounds.x + 16;
        if (item.icon) |icon_type| {
            const icon_y = current_y + @as(i32, @intCast((config.item_height - 24) / 2));
            const icon_color = if (is_selected) colors.icon_selected else colors.icon;

            icon_module.iconRect(ctx, .{
                .x = text_x,
                .y = icon_y,
                .w = 24,
                .h = 24,
            }, icon_type, .{}, .{ .foreground = icon_color });

            text_x += 40;
        }

        // Draw label
        const label_y = current_y + @as(i32, @intCast((config.item_height - 8) / 2));
        const label_color = if (item.disabled)
            colors.item_text.darken(40)
        else if (is_selected)
            colors.item_selected
        else
            colors.item_text;

        ctx.pushCommand(Command.text(text_x, label_y, item.label, label_color));

        // Draw badge
        if (item.badge) |badge_text| {
            if (badge_text.len > 0) {
                const badge_w = @max(20, badge_text.len * 8 + 8);
                const badge_x = bounds.x + @as(i32, @intCast(bounds.w)) - @as(i32, @intCast(badge_w)) - 16;
                const badge_y = current_y + @as(i32, @intCast((config.item_height - 20) / 2));

                ctx.pushCommand(Command.rect(badge_x, badge_y, @intCast(badge_w), 20, colors.badge_bg));
                ctx.pushCommand(Command.text(badge_x + 6, badge_y + 6, badge_text, colors.badge_text));
            }
        }

        current_y += @as(i32, @intCast(config.item_height));

        // Draw divider
        if (item.divider_after) {
            ctx.pushCommand(Command.rect(bounds.x + 16, current_y, bounds.w - 32, 1, colors.divider_color));
            current_y += 8;
        }
    }

    // Content rect
    const content_rect = Layout.Rect{
        .x = bounds.x + @as(i32, @intCast(bounds.w)),
        .y = 0,
        .w = ctx.layout.area.w -| bounds.w,
        .h = ctx.layout.area.h,
    };

    return .{
        .clicked = clicked,
        .bounds = bounds,
        .content_rect = content_rect,
    };
}

/// Modal navigation drawer with scrim
pub fn modalNavDrawer(
    ctx: *Context,
    state: *State,
    config: Config,
    colors: Colors,
) Result {
    // Update animation
    const target: f32 = if (state.is_open) 1.0 else 0.0;
    const speed: f32 = 0.1;
    if (state.animation_progress < target) {
        state.animation_progress = @min(target, state.animation_progress + speed);
    } else if (state.animation_progress > target) {
        state.animation_progress = @max(target, state.animation_progress - speed);
    }

    if (state.animation_progress < 0.01) {
        return .{
            .clicked = null,
            .bounds = Layout.Rect{ .x = 0, .y = 0, .w = 0, .h = 0 },
            .content_rect = Layout.Rect{
                .x = 0,
                .y = 0,
                .w = ctx.layout.area.w,
                .h = ctx.layout.area.h,
            },
        };
    }

    // Draw scrim
    const scrim_alpha = @as(u8, @intFromFloat(@as(f32, @floatFromInt(colors.scrim.a)) * state.animation_progress));
    ctx.pushCommand(Command.rect(
        0,
        0,
        ctx.layout.area.w,
        ctx.layout.area.h,
        colors.scrim.withAlpha(scrim_alpha),
    ));

    // Handle scrim click to close
    const mouse = ctx.input.mousePos();
    if (ctx.input.mouseReleased(.left) and mouse.x > @as(i32, @intCast(config.width))) {
        state.close();
    }

    // Slide in drawer
    const drawer_x = -@as(i32, @intCast(config.width)) + @as(i32, @intFromFloat(@as(f32, @floatFromInt(config.width)) * state.animation_progress));

    const bounds = Layout.Rect{
        .x = drawer_x,
        .y = 0,
        .w = config.width,
        .h = ctx.layout.area.h,
    };

    var result = navDrawerRect(ctx, bounds, state, config, colors);
    result.content_rect = Layout.Rect{
        .x = 0,
        .y = 0,
        .w = ctx.layout.area.w,
        .h = ctx.layout.area.h,
    };

    return result;
}

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

test "navDrawer state" {
    var state = State.init();
    try std.testing.expect(!state.is_open);

    state.open();
    try std.testing.expect(state.is_open);

    state.toggle();
    try std.testing.expect(!state.is_open);
}

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

    var state = State.init();

    ctx.beginFrame();

    const items = [_]NavItem{
        .{ .id = 1, .label = "Home", .icon = .home },
        .{ .id = 2, .label = "Settings", .icon = .settings },
    };

    const result = navDrawer(&ctx, &state, .{ .items = &items }, .{});

    try std.testing.expect(ctx.commands.items.len >= 3);
    try std.testing.expect(result.content_rect.x > 0);

    ctx.endFrame();
}

test "navDrawer with header" {
    var ctx = try Context.init(std.testing.allocator, 800, 600);
    defer ctx.deinit();

    var state = State.init();

    ctx.beginFrame();

    _ = navDrawer(&ctx, &state, .{
        .header = .{ .title = "My App" },
    }, .{});

    // Should include header background and title
    try std.testing.expect(ctx.commands.items.len >= 2);

    ctx.endFrame();
}

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

    var state = State.init();
    state.selected_id = 1;

    ctx.beginFrame();

    const items = [_]NavItem{
        .{ .id = 1, .label = "Home" },
        .{ .id = 2, .label = "About" },
    };

    _ = navDrawer(&ctx, &state, .{ .items = &items }, .{});

    // Selection should be visible
    try std.testing.expect(ctx.commands.items.len >= 3);

    ctx.endFrame();
}