//! Resize Widget - Draggable resize handle
//!
//! A handle that can be dragged to resize adjacent elements.
//! Used in split panels, column resizing, etc.

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");

/// Resize direction
pub const Direction = enum {
    /// Resize horizontally (left-right)
    horizontal,
    /// Resize vertically (up-down)
    vertical,
    /// Resize in both directions
    both,
};

/// Resize state
pub const State = struct {
    /// Current size (what we're controlling)
    size: i32 = 200,
    /// Is currently being dragged
    dragging: bool = false,
    /// Drag start position
    drag_start: i32 = 0,
    /// Size at drag start
    size_at_start: i32 = 0,

    pub fn init(initial_size: i32) State {
        return .{ .size = initial_size };
    }
};

/// Resize configuration
pub const Config = struct {
    /// Resize direction
    direction: Direction = .horizontal,
    /// Handle size (width for horizontal, height for vertical)
    handle_size: u16 = 8,
    /// Minimum size constraint
    min_size: i32 = 50,
    /// Maximum size constraint (null = no limit)
    max_size: ?i32 = null,
    /// Show visual handle indicator
    show_handle: bool = true,
    /// Double-click to reset to default
    double_click_reset: bool = true,
    /// Default size for reset
    default_size: i32 = 200,
};

/// Resize colors
pub const Colors = struct {
    /// Handle background
    handle: Style.Color = Style.Color.rgba(80, 80, 80, 100),
    /// Handle when hovered
    handle_hover: Style.Color = Style.Color.rgba(100, 100, 100, 150),
    /// Handle when dragging
    handle_active: Style.Color = Style.Color.rgba(66, 133, 244, 200),
    /// Grip dots
    grip: Style.Color = Style.Color.rgb(120, 120, 120),

    pub fn fromTheme(theme: Style.Theme) Colors {
        return .{
            .handle = theme.border.withAlpha(100),
            .handle_hover = theme.border.withAlpha(150),
            .handle_active = theme.primary.withAlpha(200),
            .grip = theme.foreground.darken(40),
        };
    }
};

/// Resize result
pub const Result = struct {
    /// Current size value
    size: i32,
    /// Size changed this frame
    changed: bool,
    /// Delta from last frame
    delta: i32,
    /// Handle is being hovered
    hovered: bool,
    /// Handle is being dragged
    dragging: bool,
    /// Handle bounds
    bounds: Layout.Rect,
};

/// Simple resize handle
pub fn resize(ctx: *Context, state: *State) Result {
    return resizeEx(ctx, state, .{}, .{});
}

/// Resize handle with configuration
pub fn resizeEx(ctx: *Context, state: *State, config: Config, colors: Colors) Result {
    const bounds = ctx.layout.nextRect();
    return resizeRect(ctx, bounds, state, config, colors);
}

/// Resize handle in specific rectangle
pub fn resizeRect(
    ctx: *Context,
    bounds: Layout.Rect,
    state: *State,
    config: Config,
    colors: Colors,
) Result {
    if (bounds.isEmpty()) {
        return .{
            .size = state.size,
            .changed = false,
            .delta = 0,
            .hovered = false,
            .dragging = false,
            .bounds = bounds,
        };
    }

    // Calculate handle bounds based on direction
    const handle_bounds = switch (config.direction) {
        .horizontal => Layout.Rect{
            .x = bounds.x + @as(i32, @intCast(bounds.w / 2)) - @as(i32, @intCast(config.handle_size / 2)),
            .y = bounds.y,
            .w = config.handle_size,
            .h = bounds.h,
        },
        .vertical => Layout.Rect{
            .x = bounds.x,
            .y = bounds.y + @as(i32, @intCast(bounds.h / 2)) - @as(i32, @intCast(config.handle_size / 2)),
            .w = bounds.w,
            .h = config.handle_size,
        },
        .both => Layout.Rect{
            .x = bounds.x + @as(i32, @intCast(bounds.w / 2)) - @as(i32, @intCast(config.handle_size / 2)),
            .y = bounds.y + @as(i32, @intCast(bounds.h / 2)) - @as(i32, @intCast(config.handle_size / 2)),
            .w = config.handle_size,
            .h = config.handle_size,
        },
    };

    // Mouse interaction
    const mouse = ctx.input.mousePos();
    const hovered = handle_bounds.contains(mouse.x, mouse.y);
    var changed = false;
    var delta: i32 = 0;

    // Handle drag start
    if (hovered and ctx.input.mousePressed(.left)) {
        state.dragging = true;
        state.drag_start = switch (config.direction) {
            .horizontal => mouse.x,
            .vertical => mouse.y,
            .both => mouse.x, // Primary direction
        };
        state.size_at_start = state.size;
    }

    // Handle dragging
    if (state.dragging) {
        if (ctx.input.mousePressed(.left) or ctx.input.mousePos().x != 0 or ctx.input.mousePos().y != 0) {
            const current_pos = switch (config.direction) {
                .horizontal => mouse.x,
                .vertical => mouse.y,
                .both => mouse.x,
            };
            const drag_delta = current_pos - state.drag_start;
            var new_size = state.size_at_start + drag_delta;

            // Apply constraints
            new_size = @max(config.min_size, new_size);
            if (config.max_size) |max| {
                new_size = @min(max, new_size);
            }

            if (new_size != state.size) {
                delta = new_size - state.size;
                state.size = new_size;
                changed = true;
            }
        }

        // End drag
        if (ctx.input.mouseReleased(.left)) {
            state.dragging = false;
        }
    }

    // Draw handle
    if (config.show_handle) {
        const handle_color = if (state.dragging)
            colors.handle_active
        else if (hovered)
            colors.handle_hover
        else
            colors.handle;

        ctx.pushCommand(Command.rect(
            handle_bounds.x,
            handle_bounds.y,
            handle_bounds.w,
            handle_bounds.h,
            handle_color,
        ));

        // Draw grip indicator
        drawGrip(ctx, handle_bounds, config.direction, colors.grip);
    }

    return .{
        .size = state.size,
        .changed = changed,
        .delta = delta,
        .hovered = hovered,
        .dragging = state.dragging,
        .bounds = handle_bounds,
    };
}

fn drawGrip(ctx: *Context, bounds: Layout.Rect, direction: Direction, color: Style.Color) void {
    const dot_size: u32 = 2;
    const dot_spacing: i32 = 4;
    const dot_count: i32 = 3;

    const cx = bounds.x + @as(i32, @intCast(bounds.w / 2));
    const cy = bounds.y + @as(i32, @intCast(bounds.h / 2));

    switch (direction) {
        .horizontal => {
            // Vertical line of dots
            var i: i32 = -1;
            while (i <= 1) : (i += 1) {
                ctx.pushCommand(Command.rect(
                    cx - @as(i32, @intCast(dot_size / 2)),
                    cy + i * dot_spacing - @as(i32, @intCast(dot_size / 2)),
                    dot_size,
                    dot_size,
                    color,
                ));
            }
        },
        .vertical => {
            // Horizontal line of dots
            var i: i32 = -1;
            while (i <= 1) : (i += 1) {
                ctx.pushCommand(Command.rect(
                    cx + i * dot_spacing - @as(i32, @intCast(dot_size / 2)),
                    cy - @as(i32, @intCast(dot_size / 2)),
                    dot_size,
                    dot_size,
                    color,
                ));
            }
        },
        .both => {
            // 3x3 grid of dots
            var dx: i32 = -1;
            while (dx <= 1) : (dx += 1) {
                var dy: i32 = -1;
                while (dy <= 1) : (dy += 1) {
                    if (dx == 0 and dy == 0) continue; // Skip center
                    ctx.pushCommand(Command.rect(
                        cx + dx * dot_spacing - @as(i32, @intCast(dot_size / 2)),
                        cy + dy * dot_spacing - @as(i32, @intCast(dot_size / 2)),
                        dot_size,
                        dot_size,
                        color,
                    ));
                }
            }
        },
    }
    _ = dot_count;
}

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

test "resize state init" {
    const state = State.init(300);
    try std.testing.expectEqual(@as(i32, 300), state.size);
    try std.testing.expect(!state.dragging);
}

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

    var state = State.init(200);

    ctx.beginFrame();
    ctx.layout.row_height = 400;

    const result = resize(&ctx, &state);

    // Should generate handle rect + grip dots
    try std.testing.expect(ctx.commands.items.len >= 1);
    try std.testing.expect(!result.changed);

    ctx.endFrame();
}

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

    var state = State.init(200);

    ctx.beginFrame();
    ctx.layout.row_height = 400;

    _ = resizeEx(&ctx, &state, .{ .direction = .horizontal }, .{});

    try std.testing.expect(ctx.commands.items.len >= 1);

    ctx.endFrame();
}

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

    var state = State.init(200);

    ctx.beginFrame();
    ctx.layout.row_height = 400;

    _ = resizeEx(&ctx, &state, .{ .direction = .vertical }, .{});

    try std.testing.expect(ctx.commands.items.len >= 1);

    ctx.endFrame();
}

test "resize constraints" {
    var state = State.init(200);

    // Test min constraint
    state.size = 30;
    const min: i32 = 50;
    state.size = @max(min, state.size);
    try std.testing.expect(state.size >= min);
}