package main

import (
	"encoding/base64"
	"errors"
	"net/http"
	"net/url"
	"strings"

	"github.com/playwright-community/playwright-go"
)

type RawImageFile struct {
	URL    string
	Blocks []map[string]int
	Width  *int
	Height *int
}

type File struct {
	ContentType string
	Data        []byte
}

var draw = `
async function drawImage(imageFile) {
	const canvas = Object.assign(document.createElement("canvas"), {
			width: imageFile.width,
			height: imageFile.height,
	});
	const image = (await new Promise((resolve) => {
			Object.assign(new Image(), {
					crossOrigin: "use-credentials",
					src: imageFile.url,
					onload() {
							resolve(this);
					},
			});
	}));
	const ctx = canvas.getContext("2d");
	for (const q of imageFile.blocks) {
			ctx.drawImage(image, q.destX, q.destY, q.width, q.height, q.srcX, q.srcY, q.width, q.height);
	}
	const dataUrl = canvas.toDataURL();
	return dataUrl;
}
`

var fetch = `
async function fetchImage(imageFile) {
	const res = await fetch(imageFile.url);
	const blob = await res.blob();
	const dataUrl = await new Promise((resolve, reject) => {
			const fileReader = Object.assign(new FileReader(), {
					onload() {
							resolve(this.result);
					},
					onerror(e) {
							const error = new Error(` + "`${e.type}: ${e.message}`" + `);
							reject(error);
					},
			});
			fileReader.readAsDataURL(blob);
	});
	return dataUrl;
}
`

func parseDataURL(dataURL string) (*File, error) {
	if !strings.HasPrefix(dataURL, "data:") {
		return nil, errors.New("not data scheme")
	}
	parts := strings.SplitN(dataURL, ",", 2)
	if len(parts) != 2 {
		return nil, errors.New("invalid data URL")
	}
	raw, err := url.PathUnescape(parts[1])
	if err != nil {
		return nil, err
	}

	var data []byte

	if strings.HasSuffix(parts[0], ";base64") {
		data, err = base64.StdEncoding.DecodeString(raw)
		if err != nil {
			return nil, err
		}
	} else {
		data = []byte(raw)
	}

	file := File{
		ContentType: http.DetectContentType(data),
		Data:        data,
	}

	return &file, nil
}

type BrowserContext interface {
	*playwright.BrowserContext
}

type Browser struct {
	browser playwright.Browser
}

//  TODO
//  Browser loadBrowserContext(platform: TPlatform): Promise<Playwright.BrowserContext>;
//  Browser saveBrowserContext(platform: TPlatform, ctx: BrowserContext): Promise<void>;
//  Browser newContext(): Promise<Playwright.BrowserContext>;
//  Browser close(): Promise<void>;
//  Browser drawImage(
//     pageOrFrame: Playwright.Page | Playwright.Frame,
//     imageFile: ImageFile,
//   ): Promise<Blob>;
// install

// newじゃないか? run/stop? launch/close?
func New() (*Browser, error) {
	pw, err := playwright.Run()
	if err != nil {
		return nil, err
	}
	browser, err := pw.Chromium.Launch()
	if err != nil {
		return nil, err
	}
	return &Browser{browser}, nil
}