import { point_inside_rec } from "$/common/utils.ts";
import { AssetManager } from "$/client/assets.ts";
import { InputManager } from "$/client/input_manager.ts";
import { draw_nine_slice } from "$/client/rendering/render_utils.ts";
import { draw_rect, draw_text, measure_text, Texture } from "$/client/renderer/mod.ts";

export const TEXT_SCALE = 2;
// how tall the font is at scale 1
export const TEXT_HEIGHT = 11;

const REPEAT_DELAY_MS = 400;
const REPEAT_RATE_MS = 40;
const CARET_BLINK_MS = 500;

// editing a line of text with the keyboard: typing, backspace (held repeats), delete, arrows, home and end
export class TextInput {
	value: string;
	caret: number;
	max_length: number;
	// which typed characters are kept
	allowed: (char: string) => boolean;

	#repeat_timer = 0;

	constructor(value = "", max_length = 256, allowed: (char: string) => boolean = () => true) {
		this.value = value;
		this.caret = value.length;
		this.max_length = max_length;
		this.allowed = allowed;
	}

	// call once per frame while it has the keyboard
	handle_keys() {
		const now = performance.now();
		let backspace = false;
		if (InputManager.is_key_pressed("Backspace")) {
			this.#repeat_timer = now;
			backspace = true;
		} else if (InputManager.is_key_down("Backspace") && now - this.#repeat_timer > REPEAT_DELAY_MS) {
			this.#repeat_timer = now - (REPEAT_DELAY_MS - REPEAT_RATE_MS);
			backspace = true;
		}
		if (backspace && this.caret > 0) {
			this.value = this.value.slice(0, this.caret - 1) + this.value.slice(this.caret);
			this.caret -= 1;
		}

		if (InputManager.is_key_pressed("Delete")) {
			this.value = this.value.slice(0, this.caret) + this.value.slice(this.caret + 1);
		}
		if (InputManager.is_key_pressed("ArrowLeft")) {
			this.caret = Math.max(0, this.caret - 1);
		}
		if (InputManager.is_key_pressed("ArrowRight")) {
			this.caret = Math.min(this.value.length, this.caret + 1);
		}
		if (InputManager.is_key_pressed("Home")) {
			this.caret = 0;
		}
		if (InputManager.is_key_pressed("End")) {
			this.caret = this.value.length;
		}

		for (const char of InputManager.get_typed_characters()) {
			if (this.value.length >= this.max_length || !this.allowed(char)) {
				continue;
			}
			this.value = this.value.slice(0, this.caret) + char + this.value.slice(this.caret);
			this.caret += 1;
		}
	}

	// where the caret goes when the text starts at x
	caret_x(x: number, scale = TEXT_SCALE) {
		return x + measure_text(this.value.slice(0, this.caret), scale);
	}

	static caret_visible() {
		return Math.floor(performance.now() / CARET_BLINK_MS) % 2 === 0;
	}
}

// a clickable button, like minecraft's Button
export class Button {
	x = 0;
	y = 0;
	width: number;
	height: number;
	label: string;
	on_press: () => void;
	active = true;
	#hovered = false;

	constructor(label: string, width: number, height: number, on_press: () => void) {
		this.label = label;
		this.width = width;
		this.height = height;
		this.on_press = on_press;
	}

	// returns whether it was pressed
	handle_input(): boolean {
		const mouse = InputManager.get_mouse_position();
		this.#hovered = this.active && point_inside_rec(mouse.x, mouse.y, this.x, this.y, this.width, this.height);
		if (this.#hovered && InputManager.is_mouse_pressed(0)) {
			InputManager.consume_mouse(0);
			this.on_press();
			return true;
		}
		return false;
	}

	render() {
		const ui = AssetManager.instance.get<Texture>("bworld:ui");
		const [sx, sy] = this.#hovered ? [224, 16] : [176, 0];
		const tint = this.active ? [1, 1, 1, 1] : [0.6, 0.6, 0.6, 1];
		draw_nine_slice(ui, sx, sy, 16, 16, 4, 4, 4, 4, this.x, this.y, this.width, this.height, tint);

		const text_width = measure_text(this.label, TEXT_SCALE);
		draw_text(
			this.label,
			this.x + (this.width - text_width) / 2,
			this.y + (this.height - TEXT_HEIGHT * TEXT_SCALE) / 2,
			TEXT_SCALE,
			this.active ? [1, 1, 1, 1] : [0.7, 0.7, 0.7, 1],
		);
	}
}

// a one line text field, like minecraft's EditBox. clicking it gives it the keyboard
export class EditBox {
	x = 0;
	y = 0;
	width: number;
	height: number;
	input: TextInput;
	focused = false;
	// shown greyed out while it's empty
	hint: string;
	active = true;

	constructor(width: number, height: number, input: TextInput, hint = "") {
		this.width = width;
		this.height = height;
		this.input = input;
		this.hint = hint;
	}

	get value() {
		return this.input.value;
	}

	// returns whether it was clicked, so the screen can move focus to it
	handle_input(): boolean {
		const mouse = InputManager.get_mouse_position();
		const clicked = this.active && InputManager.is_mouse_pressed(0) &&
			point_inside_rec(mouse.x, mouse.y, this.x, this.y, this.width, this.height);
		if (clicked) {
			InputManager.consume_mouse(0);
		}
		if (this.focused && this.active) {
			this.input.handle_keys();
		}
		return clicked;
	}

	render() {
		const ui = AssetManager.instance.get<Texture>("bworld:ui");
		draw_nine_slice(ui, this.focused ? 320 : 304, 0, 16, 16, 4, 4, 4, 4, this.x, this.y, this.width, this.height);

		const text_x = this.x + 10;
		const text_y = this.y + (this.height - TEXT_HEIGHT * TEXT_SCALE) / 2;
		if (this.value === "" && !this.focused) {
			draw_text(this.hint, text_x, text_y, TEXT_SCALE, [0.6, 0.6, 0.6, 1]);
		} else {
			draw_text(this.value, text_x, text_y, TEXT_SCALE, this.active ? [1, 1, 1, 1] : [0.7, 0.7, 0.7, 1]);
		}
		if (this.focused && this.active && TextInput.caret_visible()) {
			draw_rect(this.input.caret_x(text_x), text_y, 2, TEXT_HEIGHT * TEXT_SCALE);
		}
	}
}