//! Splitter Demo - Resizable panels with mouse drag
//!
//! Demonstrates mouse drag to resize panels.
//! Run with: zig build splitter-demo

const std = @import("std");
const zcatui = @import("zcatui");

const Terminal = zcatui.Terminal;
const Rect = zcatui.Rect;
const Buffer = zcatui.Buffer;
const Style = zcatui.Style;
const Color = zcatui.Color;
const Block = zcatui.widgets.Block;
const Borders = zcatui.widgets.Borders;
const DragState = zcatui.DragState;
const DragType = zcatui.DragType;
const Splitter = zcatui.Splitter;

/// State for the demo
const State = struct {
    // Horizontal splitter (splits left/right)
    h_splitter: Splitter = Splitter.horizontal(30).setMinSizes(10, 20),
    // Vertical splitter for right side (splits top/bottom)
    v_splitter: Splitter = Splitter.vertical(50).setMinSizes(5, 5),
    // Drag state
    drag_state: DragState = .{},
    // Which splitter is being dragged
    active_splitter: ActiveSplitter = .none,
    // Current area for hit testing
    current_area: Rect = Rect.init(0, 0, 80, 24),
    running: bool = true,
};

const ActiveSplitter = enum { none, horizontal, vertical };

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    var term = try Terminal.init(allocator);
    defer term.deinit();

    // Enable mouse capture for drag support
    try term.enableMouseCapture();
    term.enableAutoResize();

    var state = State{};

    while (state.running) {
        try term.drawWithContext(&state, render);

        if (try term.pollEvent(50)) |event| {
            switch (event) {
                .key => |key| {
                    switch (key.code) {
                        .char => |c| {
                            if (c == 'q') state.running = false;
                            // Keyboard shortcuts to adjust splitters
                            if (c == 'h' or c == 'H') {
                                const delta: i32 = if (c == 'H') -5 else 5;
                                state.h_splitter.adjustPosition(state.current_area, delta);
                            }
                            if (c == 'v' or c == 'V') {
                                const parts = state.h_splitter.split(state.current_area);
                                const delta: i32 = if (c == 'V') -5 else 5;
                                state.v_splitter.adjustPosition(parts.second, delta);
                            }
                        },
                        .esc => state.running = false,
                        else => {},
                    }
                },
                .mouse => |mouse| {
                    handleMouse(&state, mouse);
                },
                else => {},
            }
        }
    }
}

fn handleMouse(state: *State, mouse: zcatui.event.MouseEvent) void {
    switch (mouse.kind) {
        .down => {
            if (mouse.button == .left) {
                // Check if on horizontal splitter
                if (state.h_splitter.isOnHandle(state.current_area, mouse.column, mouse.row)) {
                    state.drag_state.start(.horizontal_resize, mouse.column, mouse.row);
                    state.active_splitter = .horizontal;
                } else {
                    // Check if on vertical splitter (in second panel)
                    const parts = state.h_splitter.split(state.current_area);
                    if (state.v_splitter.isOnHandle(parts.second, mouse.column, mouse.row)) {
                        state.drag_state.start(.vertical_resize, mouse.column, mouse.row);
                        state.active_splitter = .vertical;
                    }
                }
            }
        },
        .drag => {
            if (state.drag_state.isDragging()) {
                const old_x = state.drag_state.current_x;
                const old_y = state.drag_state.current_y;
                state.drag_state.update(mouse.column, mouse.row);

                // Apply the delta to the active splitter
                switch (state.active_splitter) {
                    .horizontal => {
                        const delta = @as(i32, mouse.column) - @as(i32, old_x);
                        if (delta != 0) {
                            state.h_splitter.adjustPosition(state.current_area, delta);
                        }
                    },
                    .vertical => {
                        const parts = state.h_splitter.split(state.current_area);
                        const delta = @as(i32, mouse.row) - @as(i32, old_y);
                        if (delta != 0) {
                            state.v_splitter.adjustPosition(parts.second, delta);
                        }
                    },
                    .none => {},
                }
            }
        },
        .up => {
            state.drag_state.end();
            state.active_splitter = .none;
        },
        else => {},
    }
}

fn render(state: *State, area: Rect, buf: *Buffer) void {
    // Store area for mouse hit testing
    state.current_area = area;

    // Get the split areas
    const h_parts = state.h_splitter.split(area);
    const v_parts = state.v_splitter.split(h_parts.second);

    // Draw left panel
    drawPanel(buf, h_parts.first, " Left Panel ", Color.blue, "This is the left panel.\n\nDrag the vertical bar to resize.\n\nOr press h/H to adjust.");

    // Draw top-right panel
    drawPanel(buf, v_parts.first, " Top Right ", Color.green, "This is the top-right panel.\n\nDrag the horizontal bar to resize.\n\nOr press v/V to adjust.");

    // Draw bottom-right panel
    drawPanel(buf, v_parts.second, " Bottom Right ", Color.yellow, "This is the bottom-right panel.\n\nTry dragging both splitters!");

    // Draw splitter handles
    drawSplitter(buf, h_parts.handle, true, state.active_splitter == .horizontal);
    drawSplitter(buf, v_parts.handle, false, state.active_splitter == .vertical);

    // Draw status bar
    var status_buf: [128]u8 = undefined;
    const status = std.fmt.bufPrint(&status_buf, "H-split: {d}% | V-split: {d}% | {s}", .{
        state.h_splitter.position,
        state.v_splitter.position,
        if (state.drag_state.isDragging()) "Dragging..." else "Drag splitters or press h/H v/V | q to quit",
    }) catch "...";
    _ = buf.setString(0, area.height -| 1, status, (Style{}).fg(Color.white).bg(Color.rgb(40, 40, 40)));
}

fn drawPanel(buf: *Buffer, area: Rect, title: []const u8, color: Color, content: []const u8) void {
    const block = Block.init()
        .title(title)
        .setBorders(Borders.all)
        .borderStyle((Style{}).fg(color));
    block.render(area, buf);

    // Draw content
    const inner = Rect.init(area.x + 1, area.y + 1, area.width -| 2, area.height -| 2);
    var y: u16 = 0;
    var lines = std.mem.splitScalar(u8, content, '\n');
    while (lines.next()) |line| {
        if (y >= inner.height) break;
        const max_len = @min(line.len, inner.width);
        _ = buf.setString(inner.x, inner.y + y, line[0..max_len], Style{});
        y += 1;
    }
}

fn drawSplitter(buf: *Buffer, handle: Rect, is_vertical: bool, is_active: bool) void {
    const color = if (is_active) Color.cyan else Color.rgb(100, 100, 100);
    const char: []const u8 = if (is_vertical) "|" else "-";

    if (is_vertical) {
        var y: u16 = 0;
        while (y < handle.height) : (y += 1) {
            _ = buf.setString(handle.x, handle.y + y, char, (Style{}).fg(color));
        }
    } else {
        var x: u16 = 0;
        while (x < handle.width) : (x += 1) {
            _ = buf.setString(handle.x + x, handle.y, char, (Style{}).fg(color));
        }
    }
}