//! Radio Button Widget - Mutually exclusive selection
//!
//! Provides:
//! - RadioButton: Single radio button
//! - RadioGroup: Group of mutually exclusive options
//!
//! Supports:
//! - Keyboard navigation (arrows, space)
//! - Mouse click
//! - Horizontal or vertical layout

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");

// =============================================================================
// Radio Option
// =============================================================================

/// Radio option definition
pub const RadioOption = struct {
    /// Option label
    label: []const u8,
    /// Option value/ID
    value: u32 = 0,
    /// Is option disabled
    disabled: bool = false,
};

// =============================================================================
// Radio State
// =============================================================================

/// Radio group state (caller-managed)
pub const RadioState = struct {
    /// Currently selected index (-1 for none)
    selected: i32 = -1,
    /// Has focus
    focused: bool = false,
    /// Focused option index (for keyboard navigation)
    focus_index: i32 = 0,

    const Self = @This();

    /// Get selected value
    pub fn getSelected(self: Self) ?usize {
        if (self.selected < 0) return null;
        return @intCast(self.selected);
    }

    /// Set selected by index
    pub fn setSelected(self: *Self, index: usize) void {
        self.selected = @intCast(index);
    }

    /// Set selected by value
    pub fn setSelectedValue(self: *Self, options: []const RadioOption, value: u32) void {
        for (options, 0..) |opt, i| {
            if (opt.value == value) {
                self.selected = @intCast(i);
                return;
            }
        }
    }

    /// Get selected value
    pub fn getSelectedValue(self: Self, options: []const RadioOption) ?u32 {
        if (self.selected < 0) return null;
        const idx: usize = @intCast(self.selected);
        if (idx >= options.len) return null;
        return options[idx].value;
    }

    /// Move focus to next option
    pub fn focusNext(self: *Self, options: []const RadioOption) void {
        if (options.len == 0) return;
        var next = self.focus_index + 1;
        var attempts: usize = 0;
        while (attempts < options.len) {
            if (next >= @as(i32, @intCast(options.len))) next = 0;
            if (!options[@intCast(next)].disabled) {
                self.focus_index = next;
                return;
            }
            next += 1;
            attempts += 1;
        }
    }

    /// Move focus to previous option
    pub fn focusPrev(self: *Self, options: []const RadioOption) void {
        if (options.len == 0) return;
        var prev = self.focus_index - 1;
        var attempts: usize = 0;
        while (attempts < options.len) {
            if (prev < 0) prev = @as(i32, @intCast(options.len)) - 1;
            if (!options[@intCast(prev)].disabled) {
                self.focus_index = prev;
                return;
            }
            prev -= 1;
            attempts += 1;
        }
    }
};

// =============================================================================
// Radio Configuration
// =============================================================================

/// Radio group layout direction
pub const Direction = enum {
    vertical,
    horizontal,
};

/// Radio configuration
pub const RadioConfig = struct {
    /// Layout direction
    direction: Direction = .vertical,
    /// Size of radio circle
    radio_size: u32 = 16,
    /// Spacing between options
    spacing: u32 = 8,
    /// Padding between radio and label
    label_padding: u32 = 8,
};

/// Radio colors
pub const RadioColors = struct {
    /// Radio circle border
    border: Style.Color = Style.Color.rgb(100, 100, 105),
    /// Radio circle border when focused
    border_focus: Style.Color = Style.Color.primary,
    /// Radio circle background
    background: Style.Color = Style.Color.rgb(40, 40, 45),
    /// Radio fill when selected
    fill: Style.Color = Style.Color.primary,
    /// Label text
    label: Style.Color = Style.Color.rgb(220, 220, 220),
    /// Disabled label text
    label_disabled: Style.Color = Style.Color.rgb(100, 100, 100),
};

/// Radio result
pub const RadioResult = struct {
    /// Selection changed
    changed: bool = false,
    /// Newly selected index
    selected: ?usize = null,
    /// Newly selected value
    value: ?u32 = null,
};

// =============================================================================
// Radio Functions
// =============================================================================

/// Draw a radio group
pub fn radioGroup(
    ctx: *Context,
    state: *RadioState,
    options: []const RadioOption,
) RadioResult {
    return radioGroupEx(ctx, state, options, .{}, .{});
}

/// Draw a radio group with configuration
pub fn radioGroupEx(
    ctx: *Context,
    state: *RadioState,
    options: []const RadioOption,
    config: RadioConfig,
    colors: RadioColors,
) RadioResult {
    const bounds = ctx.layout.nextRect();
    return radioGroupRect(ctx, bounds, state, options, config, colors);
}

/// Draw a radio group in a specific rectangle
pub fn radioGroupRect(
    ctx: *Context,
    bounds: Layout.Rect,
    state: *RadioState,
    options: []const RadioOption,
    config: RadioConfig,
    colors: RadioColors,
) RadioResult {
    var result = RadioResult{};

    if (bounds.isEmpty() or options.len == 0) return result;

    // Generate unique ID for this widget based on state address
    const widget_id: u64 = @intFromPtr(state);

    // Register as focusable in the active focus group
    ctx.registerFocusable(widget_id);

    const mouse = ctx.input.mousePos();
    const mouse_pressed = ctx.input.mousePressed(.left);

    // Check if group area clicked (for focus)
    if (mouse_pressed and bounds.contains(mouse.x, mouse.y)) {
        ctx.requestFocus(widget_id);
    }

    // Check if this widget has focus
    const has_focus = ctx.hasFocus(widget_id);
    state.focused = has_focus;

    // Draw options
    var pos_x = bounds.x;
    var pos_y = bounds.y;

    for (options, 0..) |opt, i| {
        const is_selected = state.selected == @as(i32, @intCast(i));
        const is_focused = state.focused and state.focus_index == @as(i32, @intCast(i));

        // Calculate option bounds
        const label_width: u32 = @intCast(opt.label.len * 8);
        const option_width = config.radio_size + config.label_padding + label_width;
        const option_height = @max(config.radio_size, 16);

        const option_rect = Layout.Rect.init(pos_x, pos_y, option_width, option_height);
        const is_hovered = option_rect.contains(mouse.x, mouse.y) and !opt.disabled;

        // Radio circle position
        const radio_x = pos_x;
        const radio_y = pos_y + @as(i32, @intCast((option_height -| config.radio_size) / 2));

        // Draw radio circle outline
        const border_color = if (opt.disabled)
            colors.border.darken(20)
        else if (is_focused)
            colors.border_focus
        else
            colors.border;

        // Draw outer circle (as rect, since we don't have circle primitive)
        const corner_radius: u8 = @intCast(@min(config.radio_size / 2, 8));
        if (Style.isFancy() and corner_radius > 0) {
            ctx.pushCommand(Command.roundedRectOutline(radio_x, radio_y, config.radio_size, config.radio_size, border_color, corner_radius));
            ctx.pushCommand(Command.roundedRect(radio_x + 1, radio_y + 1, config.radio_size - 2, config.radio_size - 2, colors.background, corner_radius));
            // Focus ring around the focused option
            if (is_focused) {
                ctx.pushCommand(Command.focusRing(radio_x, radio_y, config.radio_size, config.radio_size, corner_radius));
            }
        } else {
            ctx.pushCommand(Command.rectOutline(radio_x, radio_y, config.radio_size, config.radio_size, border_color));
            ctx.pushCommand(Command.rect(radio_x + 1, radio_y + 1, config.radio_size - 2, config.radio_size - 2, colors.background));
        }

        // Draw fill if selected
        if (is_selected) {
            const fill_margin: u32 = 4;
            const fill_size = config.radio_size -| (fill_margin * 2);
            const fill_color = if (opt.disabled) colors.fill.darken(30) else colors.fill;
            const fill_radius: u8 = @intCast(@min(fill_size / 2, 6));
            if (Style.isFancy() and fill_radius > 0) {
                ctx.pushCommand(Command.roundedRect(
                    radio_x + @as(i32, @intCast(fill_margin)),
                    radio_y + @as(i32, @intCast(fill_margin)),
                    fill_size,
                    fill_size,
                    fill_color,
                    fill_radius,
                ));
            } else {
                ctx.pushCommand(Command.rect(
                    radio_x + @as(i32, @intCast(fill_margin)),
                    radio_y + @as(i32, @intCast(fill_margin)),
                    fill_size,
                    fill_size,
                    fill_color,
                ));
            }
        }

        // Draw label
        const label_x = pos_x + @as(i32, @intCast(config.radio_size + config.label_padding));
        const label_y = pos_y + @as(i32, @intCast((option_height -| 8) / 2));
        const label_color = if (opt.disabled) colors.label_disabled else colors.label;
        ctx.pushCommand(Command.text(label_x, label_y, opt.label, label_color));

        // Handle click
        if (mouse_pressed and is_hovered) {
            if (state.selected != @as(i32, @intCast(i))) {
                state.selected = @intCast(i);
                state.focus_index = @intCast(i);
                result.changed = true;
                result.selected = i;
                result.value = opt.value;
            }
        }

        // Update position for next option
        if (config.direction == .vertical) {
            pos_y += @as(i32, @intCast(option_height + config.spacing));
        } else {
            pos_x += @as(i32, @intCast(option_width + config.spacing));
        }
    }

    // Handle keyboard navigation
    if (state.focused) {
        const nav_prev = if (config.direction == .vertical)
            ctx.input.keyPressed(.up)
        else
            ctx.input.keyPressed(.left);

        const nav_next = if (config.direction == .vertical)
            ctx.input.keyPressed(.down)
        else
            ctx.input.keyPressed(.right);

        if (nav_prev) {
            state.focusPrev(options);
        }
        if (nav_next) {
            state.focusNext(options);
        }
        if (ctx.input.keyPressed(.space) or ctx.input.keyPressed(.enter)) {
            const focus_idx: usize = @intCast(state.focus_index);
            if (focus_idx < options.len and !options[focus_idx].disabled) {
                if (state.selected != state.focus_index) {
                    state.selected = state.focus_index;
                    result.changed = true;
                    result.selected = focus_idx;
                    result.value = options[focus_idx].value;
                }
            }
        }
    }

    return result;
}

// =============================================================================
// Single Radio Button
// =============================================================================

/// Draw a single radio button (for custom layouts)
pub fn radioButton(
    ctx: *Context,
    label: []const u8,
    selected: bool,
    disabled: bool,
) bool {
    return radioButtonEx(ctx, label, selected, disabled, .{}, .{});
}

/// Draw a single radio button with configuration
pub fn radioButtonEx(
    ctx: *Context,
    label: []const u8,
    selected: bool,
    disabled: bool,
    config: RadioConfig,
    colors: RadioColors,
) bool {
    const bounds = ctx.layout.nextRect();

    if (bounds.isEmpty()) return false;

    const mouse = ctx.input.mousePos();
    const mouse_pressed = ctx.input.mousePressed(.left);

    const is_hovered = bounds.contains(mouse.x, mouse.y) and !disabled;
    var clicked = false;

    // Radio circle position
    const radio_x = bounds.x;
    const radio_y = bounds.y + @as(i32, @intCast((bounds.h -| config.radio_size) / 2));

    // Draw radio circle outline
    const border_color = if (disabled) colors.border.darken(20) else colors.border;
    ctx.pushCommand(Command.rectOutline(radio_x, radio_y, config.radio_size, config.radio_size, border_color));
    ctx.pushCommand(Command.rect(radio_x + 1, radio_y + 1, config.radio_size - 2, config.radio_size - 2, colors.background));

    // Draw fill if selected
    if (selected) {
        const fill_margin: u32 = 4;
        const fill_size = config.radio_size -| (fill_margin * 2);
        ctx.pushCommand(Command.rect(
            radio_x + @as(i32, @intCast(fill_margin)),
            radio_y + @as(i32, @intCast(fill_margin)),
            fill_size,
            fill_size,
            if (disabled) colors.fill.darken(30) else colors.fill,
        ));
    }

    // Draw label
    const label_x = bounds.x + @as(i32, @intCast(config.radio_size + config.label_padding));
    const label_y = bounds.y + @as(i32, @intCast((bounds.h -| 8) / 2));
    const label_color = if (disabled) colors.label_disabled else colors.label;
    ctx.pushCommand(Command.text(label_x, label_y, label, label_color));

    // Handle click
    if (mouse_pressed and is_hovered) {
        clicked = true;
    }

    return clicked;
}

// =============================================================================
// Convenience Functions
// =============================================================================

/// Create radio group from string labels
pub fn radioFromLabels(
    ctx: *Context,
    state: *RadioState,
    labels: []const []const u8,
) RadioResult {
    var options: [32]RadioOption = undefined;
    const count = @min(labels.len, options.len);

    for (0..count) |i| {
        options[i] = .{ .label = labels[i], .value = @intCast(i) };
    }

    return radioGroup(ctx, state, options[0..count]);
}

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

test "RadioState focus navigation" {
    const options = [_]RadioOption{
        .{ .label = "Option 1" },
        .{ .label = "Option 2", .disabled = true },
        .{ .label = "Option 3" },
    };

    var state = RadioState{ .focus_index = 0 };

    state.focusNext(&options);
    try std.testing.expectEqual(@as(i32, 2), state.focus_index); // Skips disabled

    state.focusNext(&options);
    try std.testing.expectEqual(@as(i32, 0), state.focus_index); // Wraps

    state.focusPrev(&options);
    try std.testing.expectEqual(@as(i32, 2), state.focus_index); // Wraps back, skips disabled
}

test "RadioState getSelectedValue" {
    const options = [_]RadioOption{
        .{ .label = "A", .value = 10 },
        .{ .label = "B", .value = 20 },
        .{ .label = "C", .value = 30 },
    };

    var state = RadioState{ .selected = 1 };
    try std.testing.expectEqual(@as(?u32, 20), state.getSelectedValue(&options));

    state.selected = -1;
    try std.testing.expectEqual(@as(?u32, null), state.getSelectedValue(&options));
}

test "RadioState setSelectedValue" {
    const options = [_]RadioOption{
        .{ .label = "A", .value = 10 },
        .{ .label = "B", .value = 20 },
        .{ .label = "C", .value = 30 },
    };

    var state = RadioState{};
    state.setSelectedValue(&options, 20);
    try std.testing.expectEqual(@as(i32, 1), state.selected);

    state.setSelectedValue(&options, 30);
    try std.testing.expectEqual(@as(i32, 2), state.selected);
}

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

    var state = RadioState{ .selected = 0 };
    const options = [_]RadioOption{
        .{ .label = "Option A" },
        .{ .label = "Option B" },
    };

    ctx.beginFrame();
    ctx.layout.row_height = 100;

    _ = radioGroup(&ctx, &state, &options);

    // Should generate: outline + bg + fill (for selected) + label per option
    try std.testing.expect(ctx.commands.items.len >= 5);

    ctx.endFrame();
}