//! Switch Widget - Toggle on/off control
//!
//! A toggle switch similar to iOS/Android switches.
//! More visual than a checkbox, typically used for settings.

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");

/// Switch state
pub const State = struct {
    /// Current on/off state
    is_on: bool = false,
    /// Animation progress (0.0 = off position, 1.0 = on position)
    animation_progress: f32 = 0,
    /// Internal: last frame time for animation
    _last_update: i64 = 0,

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

/// Switch configuration
pub const Config = struct {
    /// Label text (appears to the right)
    label: []const u8 = "",
    /// Disabled state
    disabled: bool = false,
    /// Track dimensions
    track_width: u16 = 44,
    track_height: u16 = 24,
    /// Thumb (circle) size
    thumb_size: u16 = 20,
    /// Gap between switch and label
    gap: u16 = 8,
    /// Animation duration in ms (0 = instant)
    animation_ms: u16 = 150,
    /// Label position
    label_position: enum { left, right } = .right,
};

/// Switch colors
pub const Colors = struct {
    /// Track color when off
    track_off: Style.Color = Style.Color.rgba(100, 100, 100, 255),
    /// Track color when on
    track_on: Style.Color = Style.Color.rgba(76, 175, 80, 255), // Green
    /// Track color when disabled
    track_disabled: Style.Color = Style.Color.rgba(60, 60, 60, 255),
    /// Thumb color
    thumb: Style.Color = Style.Color.white,
    /// Thumb color when disabled
    thumb_disabled: Style.Color = Style.Color.rgba(180, 180, 180, 255),
    /// Label color
    label_color: Style.Color = Style.Color.rgba(220, 220, 220, 255),
    /// Label color when disabled
    label_disabled: Style.Color = Style.Color.rgba(120, 120, 120, 255),

    pub fn fromTheme(theme: Style.Theme) Colors {
        return .{
            .track_off = theme.secondary,
            .track_on = theme.success,
            .track_disabled = theme.secondary.darken(30),
            .thumb = Style.Color.white,
            .thumb_disabled = theme.foreground.darken(40),
            .label_color = theme.foreground,
            .label_disabled = theme.foreground.darken(40),
        };
    }
};

/// Switch result
pub const Result = struct {
    /// True if state was toggled this frame
    changed: bool,
    /// True if switch is currently hovered
    hovered: bool,
    /// Current on/off state
    is_on: bool,
};

/// Simple switch with just a label
pub fn switch_(ctx: *Context, state: *State, label_text: []const u8) Result {
    return switchEx(ctx, state, .{ .label = label_text }, .{});
}

/// Switch with custom configuration
pub fn switchEx(ctx: *Context, state: *State, config: Config, colors: Colors) Result {
    const bounds = ctx.layout.nextRect();
    return switchRect(ctx, bounds, state, config, colors);
}

/// Switch in a specific rectangle
pub fn switchRect(
    ctx: *Context,
    bounds: Layout.Rect,
    state: *State,
    config: Config,
    colors: Colors,
) Result {
    if (bounds.isEmpty()) return .{ .changed = false, .hovered = false, .is_on = state.is_on };

    // Update animation
    updateAnimation(state, config);

    // Check mouse interaction
    const mouse = ctx.input.mousePos();
    const switch_width = config.track_width;

    // Calculate switch position based on label position
    const switch_x = if (config.label_position == .left and config.label.len > 0)
        bounds.x + @as(i32, @intCast(config.label.len * 8 + config.gap))
    else
        bounds.x;

    const switch_rect = Layout.Rect{
        .x = switch_x,
        .y = bounds.y + @as(i32, @intCast((bounds.h -| config.track_height) / 2)),
        .w = switch_width,
        .h = config.track_height,
    };

    const hovered = switch_rect.contains(mouse.x, mouse.y) and !config.disabled;
    const clicked = hovered and ctx.input.mouseReleased(.left);

    // Toggle on click
    var changed = false;
    if (clicked) {
        state.is_on = !state.is_on;
        changed = true;
    }

    // Draw track
    const track_color = if (config.disabled)
        colors.track_disabled
    else
        blendColors(colors.track_off, colors.track_on, state.animation_progress);

    // Draw rounded track
    drawRoundedRect(ctx, switch_rect, config.track_height / 2, track_color);

    // Draw thumb
    const thumb_margin: i32 = @intCast((config.track_height - config.thumb_size) / 2);
    const thumb_travel: f32 = @floatFromInt(config.track_width - config.thumb_size - @as(u16, @intCast(thumb_margin * 2)));
    const thumb_offset: i32 = @intFromFloat(thumb_travel * state.animation_progress);

    const thumb_x = switch_rect.x + thumb_margin + thumb_offset;
    const thumb_y = switch_rect.y + thumb_margin;
    const thumb_color = if (config.disabled) colors.thumb_disabled else colors.thumb;

    // Draw thumb as filled circle (approximated with rounded rect)
    drawRoundedRect(ctx, .{
        .x = thumb_x,
        .y = thumb_y,
        .w = config.thumb_size,
        .h = config.thumb_size,
    }, config.thumb_size / 2, thumb_color);

    // Draw hover highlight
    if (hovered) {
        // Subtle highlight around thumb
        const highlight_size = config.thumb_size + 4;
        const highlight_x = thumb_x - 2;
        const highlight_y = thumb_y - 2;
        drawRoundedRect(ctx, .{
            .x = highlight_x,
            .y = highlight_y,
            .w = highlight_size,
            .h = highlight_size,
        }, highlight_size / 2, Style.Color.rgba(255, 255, 255, 30));
    }

    // Draw label
    if (config.label.len > 0) {
        const char_height: u32 = 8;
        const label_y = bounds.y + @as(i32, @intCast((bounds.h -| char_height) / 2));
        const label_color = if (config.disabled) colors.label_disabled else colors.label_color;

        const label_x = if (config.label_position == .left)
            bounds.x
        else
            switch_rect.x + @as(i32, @intCast(config.track_width + config.gap));

        ctx.pushCommand(Command.text(label_x, label_y, config.label, label_color));
    }

    return .{
        .changed = changed,
        .hovered = hovered,
        .is_on = state.is_on,
    };
}

/// Update animation progress
fn updateAnimation(state: *State, config: Config) void {
    if (config.animation_ms == 0) {
        // Instant transition
        state.animation_progress = if (state.is_on) 1.0 else 0.0;
        return;
    }

    const target: f32 = if (state.is_on) 1.0 else 0.0;
    const diff = target - state.animation_progress;

    if (@abs(diff) < 0.01) {
        state.animation_progress = target;
        return;
    }

    // Simple lerp animation (assumes ~16ms per frame)
    const speed: f32 = 16.0 / @as(f32, @floatFromInt(config.animation_ms));
    if (diff > 0) {
        state.animation_progress = @min(target, state.animation_progress + speed);
    } else {
        state.animation_progress = @max(target, state.animation_progress - speed);
    }
}

/// Blend two colors based on factor (0.0 = a, 1.0 = b)
fn blendColors(a: Style.Color, b: Style.Color, factor: f32) Style.Color {
    const f = @max(0.0, @min(1.0, factor));
    const inv_f = 1.0 - f;
    return Style.Color.rgba(
        @intFromFloat(@as(f32, @floatFromInt(a.r)) * inv_f + @as(f32, @floatFromInt(b.r)) * f),
        @intFromFloat(@as(f32, @floatFromInt(a.g)) * inv_f + @as(f32, @floatFromInt(b.g)) * f),
        @intFromFloat(@as(f32, @floatFromInt(a.b)) * inv_f + @as(f32, @floatFromInt(b.b)) * f),
        @intFromFloat(@as(f32, @floatFromInt(a.a)) * inv_f + @as(f32, @floatFromInt(b.a)) * f),
    );
}

/// Draw a rounded rectangle (approximated)
fn drawRoundedRect(ctx: *Context, rect: Layout.Rect, radius: u16, color: Style.Color) void {
    // For now, just draw a regular rectangle
    // TODO: Use proper rounded rect when available
    ctx.pushCommand(Command.rect(rect.x, rect.y, rect.w, rect.h, color));

    // Draw corner circles to approximate rounding
    if (radius > 0 and rect.w >= radius * 2 and rect.h >= radius * 2) {
        // This is a simplified version - real implementation would use proper AA circles
        // For now, the basic rect is fine
    }
}

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

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

    var state = State.init(false);

    // Frame 1: Click inside switch
    ctx.beginFrame();
    ctx.layout.row_height = 32;
    ctx.input.setMousePos(22, 16); // Center of switch
    ctx.input.setMouseButton(.left, true);
    _ = switch_(&ctx, &state, "Enable");
    ctx.endFrame();

    // Frame 2: Release
    ctx.beginFrame();
    ctx.layout.row_height = 32;
    ctx.input.setMousePos(22, 16);
    ctx.input.setMouseButton(.left, false);
    const result = switch_(&ctx, &state, "Enable");
    ctx.endFrame();

    try std.testing.expect(result.changed);
    try std.testing.expect(result.is_on);
    try std.testing.expect(state.is_on);
}

test "switch animation progress" {
    var state = State.init(false);
    try std.testing.expectEqual(@as(f32, 0.0), state.animation_progress);

    state.is_on = true;
    updateAnimation(&state, .{ .animation_ms = 0 });
    try std.testing.expectEqual(@as(f32, 1.0), state.animation_progress);
}

test "switch disabled no toggle" {
    var ctx = try Context.init(std.testing.allocator, 800, 600);
    defer ctx.deinit();

    var state = State.init(false);

    // Frame 1: Click
    ctx.beginFrame();
    ctx.layout.row_height = 32;
    ctx.input.setMousePos(22, 16);
    ctx.input.setMouseButton(.left, true);
    _ = switchEx(&ctx, &state, .{ .label = "Disabled", .disabled = true }, .{});
    ctx.endFrame();

    // Frame 2: Release
    ctx.beginFrame();
    ctx.layout.row_height = 32;
    ctx.input.setMousePos(22, 16);
    ctx.input.setMouseButton(.left, false);
    const result = switchEx(&ctx, &state, .{ .label = "Disabled", .disabled = true }, .{});
    ctx.endFrame();

    try std.testing.expect(!result.changed);
    try std.testing.expect(!result.is_on);
}

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

    var state = State.init(true);

    ctx.beginFrame();
    ctx.layout.row_height = 32;
    _ = switch_(&ctx, &state, "With label");
    ctx.endFrame();

    // Should generate: track rect + thumb rect + text
    try std.testing.expect(ctx.commands.items.len >= 3);
}

test "color blending" {
    const black = Style.Color.rgba(0, 0, 0, 255);
    const white = Style.Color.rgba(255, 255, 255, 255);

    const mid = blendColors(black, white, 0.5);
    try std.testing.expect(mid.r >= 127 and mid.r <= 128);
    try std.testing.expect(mid.g >= 127 and mid.g <= 128);
    try std.testing.expect(mid.b >= 127 and mid.b <= 128);

    const full_black = blendColors(black, white, 0.0);
    try std.testing.expectEqual(@as(u8, 0), full_black.r);

    const full_white = blendColors(black, white, 1.0);
    try std.testing.expectEqual(@as(u8, 255), full_white.r);
}