package main

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"text/template"

	"git.unistack.org/unistack-org/pkgdash/internal/modules"
	yamlcodec "go.unistack.org/micro-codec-yaml/v4"
	envconfig "go.unistack.org/micro-config-env/v4"
	fileconfig "go.unistack.org/micro-config-file/v4"
	"go.unistack.org/micro/v4/config"
	"go.unistack.org/micro/v4/logger"
	"go.unistack.org/micro/v4/options"
	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
)

// https://docs.github.com/ru/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file

var (
	DefaultPullRequestTitle = `Bump {{.Name}} from {{.VersionOld}} to {{.VersionNew}}`
	DefaultPullRequestBody  = `Bumps {{.Name}} from {{.VersionOld}} to {{.VersionNew}}.`
)

type Config struct {
	PullRequestTitle string `json:"pull_request_title" yaml:"pull_request_title"`
	PullRequestBody  string `json:"pull_request_body" yaml:"pull_request_body"`
}

var (
	configFiles = []string{
		"dependabot.yml",
		"pkgdash.yml",
		"pkgdash.yaml",
	}
	configDirs = []string{
		".gitea",
		".github",
		".gitlab",
	}
	repoMgmt = map[string]string{
		".gitea":  "gitea",
		".gogs":   "gogs",
		".github": "github",
		".gitlab": "gitlab",
	}
)

type Data struct {
	Modules []module.Version
}

func main() {
	var err error

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	cfg := &Config{}

	if err = config.Load(ctx,
		[]config.Config{
			config.NewConfig(
				config.Struct(cfg),
			),

			envconfig.NewConfig(
				config.Struct(cfg),
			),
		},
		config.LoadOverride(true),
	); err != nil {
		logger.Fatalf(ctx, "failed to load config: %v", err)
	}

	for _, configDir := range configDirs {
		for _, configFile := range configFiles {
			c := fileconfig.NewConfig(
				config.AllowFail(true),
				config.Struct(cfg),
				options.Codec(yamlcodec.NewCodec()),
				fileconfig.Path(filepath.Join(configDir, configFile)),
			)
			if err = c.Load(ctx, config.LoadOverride(true)); err != nil {
				logger.Fatalf(ctx, "failed to load config: %v", err)
			}
		}
	}

	path := "."
	if len(os.Args) > 1 {
		path = os.Args[1]
	}

	name, err := modules.FindModFile(path)
	if err != nil {
		panic(err)
	}
	buf, err := os.ReadFile(name)
	if err != nil {
		panic(err)
	}
	mfile, err := modfile.Parse(name, buf, nil)
	if err != nil {
		panic(err)
	}

	mvs := make(map[string]modules.Update)

	updateOptions := modules.UpdateOptions{
		Pre:    false,
		Major:  false,
		Cached: true,
		OnUpdate: func(u modules.Update) {
			if u.Err != nil {
				logger.Errorf(ctx, "%s: failed: %v", u.Module.Path, u.Err)
				return
			}
			mvs[u.Module.Path] = u
		},
	}

	for _, req := range mfile.Require {
		updateOptions.Modules = append(updateOptions.Modules, req.Mod)
	}

	modules.Updates(updateOptions)

	for path, u := range mvs {
		fmt.Printf("%s from %s to %s\n", path, u.Module.Version, u.Version)
	}

	repoMgmt := getRepoMgmt()
	if repoMgmt == "unknown" {
		logger.Fatalf(ctx, "failed to get repo management")
	}

	switch repoMgmt {
	case "gitea":
		err = giteaPullRequest(ctx, mvs)
	}

	if err != nil {
		logger.Fatalf(ctx, "failed to create pr: %v", err)
	}
}

func getRepoMgmt() string {
	for _, configDir := range configDirs {
		_, err := os.Stat(configDir)
		if err != nil {
			continue
		}
		if name, ok := repoMgmt[configDir]; ok {
			return name
		}
	}

	return "unknown"
}

func giteaPullRequest(ctx context.Context, cfg *Config, mods []module.Version) error {
	envAPIURL := os.Getenv("GITHUB_API_URL")
	envREPOSITORY := os.Getenv("GITHUB_REPOSITORY")
	envTOKEN := os.Getenv("GITHUB_TOKEN")

	var buf []byte
	var err error

	data := &Data{Modules: mods}

	tplTitle, err := template.New("pull_request_title").Parse(cfg.PullRequestTitle)
	if err != nil {
		logger.Fatalf(ctx, "failed to parse template: %v", err)
	}

	wTitle := bytes.NewBuffer(nil)

	if err = tplTitle.Execute(wTitle, data); err != nil {
		logger.Fatalf(ctx, "failed to execute template: %v", err)
	}

	tplBody, err := template.New("pull_request_title").Parse(cfg.PullRequestBody)
	if err != nil {
		logger.Fatalf(ctx, "failed to parse template: %v", err)
	}

	wBody := bytes.NewBuffer(nil)

	if err = tplBody.Execute(wBody, data); err != nil {
		logger.Fatalf(ctx, "failed to execute template: %v", err)
	}

	for _, mod := range mods {
		body := map[string]string{
			"base":  "",
			"body":  "",
			"head":  "",
			"title": "",
		}
		buf, err := json.Marshal(body)
		if err != nil {
			return err
		}
		/*
			'https://try.gitea.io/api/v1/repos/org/repo/pulls?token=myaccesstoken' \
			  -H 'accept: application/json' \
			  -H 'Content-Type: application/json' \
			  -d '{
			  "base": "main",
			  "body": "This is a PR",
			  "head": "username:feature-branch",
			  "title": "PR title"
		*/

		req, err := http.NewRequestWithContext(ctx, http.MethodPost, envAPIURL+"/repos/"+envREPOSITORY+"/pulls?token="+envTOKEN, bytes.NewReader(buf))
		if err != nil {
			return err
		}
		req.Header.Add("Accept", "application/json")
		req.Header.Add("Content-Type", "application/json")

		rsp, err := http.DefaultClient.Do(req)
		if err != nil {
			return err
		}
		if rsp.StatusCode != http.StatusOK {
			return fmt.Errorf("unknown error")
		}
	}

	return nil
}