// 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 (
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path"
	"path/filepath"
)

type WebhookCFG struct {
	Forgejo
	PageDir string
	GitDir  string
	GitUser string
	GitPass string
}

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
}

func (c *WebhookCFG) download(user, repo string) (err error) {
	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
}

type webhookPayload struct {
	Ref        string `json:"ref"`
	Repository struct {
		FullName string `json:"full_name"`
	} `json:"repository"`
}

func (c *WebhookCFG) handle(w http.ResponseWriter, r *http.Request) {
	fmt.Println("Received webhook event")
	ev := r.Header.Get("X-GitHub-Event")
	if ev != "push" {
		// skip non-push events
		fmt.Println("Skip non-push event: ", ev)
		return
	}
	defer r.Body.Close()

	data, err := io.ReadAll(r.Body)
	if err != nil {
		fmt.Println("Failed to read request body: ", err)
		return
	}

	var payload webhookPayload
	err = json.Unmarshal(data, &payload)
	if err != nil {
		fmt.Println("Failed to parse request body: ", err)
		fmt.Println("=========== Dump body: ============")
		fmt.Println(string(data))
		fmt.Println("===================================")
		return
	}

	if payload.Ref != "refs/heads/"+c.Branch {
		// skip non-branch events
		fmt.Println("Skip different branch: ", payload.Ref)
		return
	}

	user, repo := path.Split(payload.Repository.FullName)
	user = user[:len(user)-1]
	fmt.Println("Pulling ", user, repo)
	err = c.download(user, repo)
	if err != nil {
		fmt.Println("Failed to download repository: ", err)
		return
	}
}

func UseWebhook(bind string, cfg *WebhookCFG) (*http.Server, error) {
	if cfg == nil {
		return nil, errors.New("webhook config is nil")
	}
	s := &http.Server{
		Addr:    bind,
		Handler: http.HandlerFunc(cfg.handle),
	}
	return s, nil
}