// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.

package lib

import (
	"context"
	"fmt"
	"net/url"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"sync"
)

type repoSpec struct {
	user string
	name string
}

type GitRunner struct {
	ch  <-chan repoSpec
	cfg *WebhookCFG
}

func (g *GitRunner) Run(ctx context.Context) error {
	// graceful: exit only if all tasks are done
	for {
		select {
		case repo := <-g.ch:
			err := g.cfg.download(repo.user, repo.name)
			if err != nil {
				fmt.Println("Failed to download repo: ", err)
			}
		case <-ctx.Done():
			return ctx.Err()
		}
	}
}

func (c *WebhookCFG) pageDir(user, repo string) string {
	return filepath.Join(c.PageDir, user, repo)
}

func (c *WebhookCFG) gitDir(user, repo string) string {
	return filepath.Join(c.GitDir, user, repo)
}

func (c *WebhookCFG) checkout(user, repo string) (err error) {
	pageDir := c.pageDir(user, repo)
	gitDir := c.gitDir(user, repo)

	git := exec.Command(
		"git",
		"--git-dir", gitDir,
		"--work-tree", pageDir,
		"checkout", "origin/"+c.Branch,
	)
	output, err := git.CombinedOutput()
	if err != nil {
		fmt.Println("git checkout failed: ", err)
		fmt.Println("=========== Dump output: ============")
		fmt.Println(string(output))
		fmt.Println("=====================================")
	}

	return
}

func (c *WebhookCFG) fetch(user, repo string) (err error) {
	gitDir := c.gitDir(user, repo)
	git := exec.Command(
		"git",
		"--git-dir", gitDir,
		"fetch", "origin", c.Branch,
	)
	output, err := git.CombinedOutput()
	if err != nil {
		fmt.Println("git fetch failed: ", err)
		fmt.Println("=========== Dump output: ============")
		fmt.Println(string(output))
		fmt.Println("=====================================")
	}

	return
}

func (c *WebhookCFG) clone(user, repo string) (err error) {
	pageDir := c.pageDir(user, repo)
	err = os.MkdirAll(filepath.Dir(pageDir), 0755)
	if err != nil {
		return
	}

	gitDir := c.gitDir(user, repo)
	err = os.MkdirAll(filepath.Dir(gitDir), 0700)
	if err != nil {
		return
	}

	uri := c.Server
	uri.Path = "/" + path.Join(user, repo) + ".git"
	uri.User = url.UserPassword(c.GitUser, c.GitPass)

	git := exec.Command(
		"git",
		"clone",
		"-b", c.Branch,
		"--single-branch",
		"--no-tags",
		"--separate-git-dir", gitDir,
		uri.String(),
		pageDir,
	)
	output, err := git.CombinedOutput()
	if err != nil {
		fmt.Println("git clone failed: ", err)
		fmt.Println("=========== Dump output: ============")
		fmt.Println(string(output))
		fmt.Println("=====================================")
	}

	os.Remove(filepath.Join(pageDir, ".git"))

	return
}

var repoLock = &sync.Map{}

func (c *WebhookCFG) lock(user, repo string) func() {
	key := user + "/" + repo

	lock, _ := repoLock.LoadOrStore(key, &sync.Mutex{})
	m := lock.(*sync.Mutex)
	m.Lock()
	return m.Unlock
}

func (c *WebhookCFG) download(user, repo string) (err error) {
	unlock := c.lock(user, repo)
	defer unlock()
	fmt.Println("Pulling ", user, repo)

	gitDir := c.gitDir(user, repo)
	if _, err = os.Stat(gitDir); os.IsNotExist(err) {
		err = c.clone(user, repo)
	} else {
		err = c.fetch(user, repo)
	}

	if err != nil {
		return
	}

	err = c.checkout(user, repo)
	return
}