package main

import (
	"encoding/base64"
	"encoding/json"
	"errors"
	"log"
	"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
}

type browser struct {
	db      *database
	pw      *playwright.Playwright
	browser *playwright.Browser
}

func installBrowser() error {
	opts := playwright.RunOptions{
		Browsers: []string{"chromium"},
		Verbose:  true,
	}

	return playwright.Install(&opts)
}

type runOptions struct {
	db       *database
	headless bool
}

func runBrowser(options runOptions) *browser {
	pw, err := playwright.Run()
	if err != nil {
		log.Fatal(err)
	}

	launchOptions := playwright.BrowserTypeLaunchOptions{
		Headless: playwright.Bool(options.headless),
	}

	b, err := pw.Chromium.Launch(launchOptions)
	if err != nil {
		log.Fatal(err)
	}

	browser := browser{
		db:      options.db,
		pw:      pw,
		browser: &b,
	}

	return &browser
}

func (b browser) stop() error {
	if b.browser != nil {
		(*b.browser).Close()
	}

	return b.pw.Stop()
}

func (b browser) newContext() (playwright.BrowserContext, error) {
	browser := *b.browser

	return browser.NewContext()
}

func (b browser) loadBrowserContext(platform string) (playwright.BrowserContext, error) {
	var secrets string
	row := b.db.QueryRow("select secrets from platforms where name = $1", platform)
	if err := row.Scan(&secrets); err != nil {
		return nil, err
	}

	var storageState playwright.OptionalStorageState
	if err := json.Unmarshal([]byte(secrets), &storageState); err != nil {
		return nil, err
	}

	browserNewContextOptions := playwright.BrowserNewContextOptions{
		StorageState: &storageState,
	}

	ctx, err := (*b.browser).NewContext(browserNewContextOptions)
	if err != nil {
		return nil, err
	}

	return ctx, nil
}

func (b browser) saveBrowserContext(platform string, ctx playwright.BrowserContext) error {
	storageState, err := ctx.StorageState()
	if err != nil {
		return err
	}

	secrets, err := json.Marshal(storageState)
	if err != nil {
		return err
	}

	if _, err := b.db.Exec("update platforms set secrets = $1 where name = $2", secrets, platform); err != nil {
		return err
	}

	return nil
}

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
}

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 (b browser) drawImage(page playwright.Page, imageFile rawImageFile) (*file, error) {
	if len(imageFile.blocks) > 0 {
		dataURL, err := page.Evaluate(draw, imageFile)
		if err != nil {
			return nil, err
		}

		return parseDataURL(dataURL.(string))
	}

	if strings.HasPrefix(imageFile.url, "blob:") {
		dataURL, err := page.Evaluate(fetch, imageFile)
		if err != nil {
			return nil, err
		}

		return parseDataURL(dataURL.(string))
	}

	res, err := page.Context().Request().Get(imageFile.url)
	if err != nil {
		return nil, err
	}

	data, err := res.Body()
	if err != nil {
		return nil, err
	}

	file := file{
		contentType: http.DetectContentType(data),
		data:        data,
	}

	return &file, nil
}