package playground

import (
	"context"
	"crypto/md5"
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"
)

var shareURL = "https://play.golang.org/share"

var cache = make(map[string]Code)

// Code is a playground code
type Code string

func (c Code) URL() string {
	return fmt.Sprintf("https://play.golang.org/p/%s", c)
}

// Share creates a share link from text
func Share(ctx context.Context, contents string) (Code, error) {
	return share(ctx, contents)
}

// ShareFile creates a share link from a file
func ShareFile(ctx context.Context, path string) (Code, error) {
	stat, err := os.Stat(path)
	if err != nil {
		return "", fmt.Errorf("could not stat file: %w", err)
	}

	if stat.IsDir() {
		return "", fmt.Errorf("%s is a directory, not a file", path)
	}

	if !strings.HasSuffix(stat.Name(), ".go") {
		return "", fmt.Errorf("%s is not a Go file", path)
	}

	fi, err := os.Open(path)
	if err != nil {
		return "", fmt.Errorf("could not open file: %w", err)
	}
	defer fi.Close()

	contents, err := io.ReadAll(fi)
	if err != nil {
		return "", fmt.Errorf("could not read file: %w", err)
	}

	return share(ctx, string(contents))
}

func share(ctx context.Context, contents string) (Code, error) {
	hash := fmt.Sprintf("%x", md5.Sum([]byte(contents)))
	if link, ok := cache[hash]; ok {
		return link, nil
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, shareURL, strings.NewReader(contents))
	if err != nil {
		return "", fmt.Errorf("could not create request: %w", err)
	}
	req.Header.Set("User-Agent", "git.jojodev.com/golang/go-playground")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", fmt.Errorf("could not create share link: %w", err)
	}
	defer res.Body.Close()

	b, err := io.ReadAll(res.Body)
	if err != nil {
		return "", fmt.Errorf("could not read response body: %w", err)
	}

	cache[hash] = Code(b)
	return cache[hash], nil
}