package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"sync"

	"gopkg.in/ini.v1"
)

// GetConfig fetch configuration
func (config *Config) GetConfig() error {
	var configfile string

	var globalconfig GlobalConfig
	var githubconfig GitHubConfig
	var gogsconfig GogsConfig

	flag.Usage = Usage

	flag.StringVar(&configfile, "configfile", "github-to-gogs.ini", "config file to use with github-to-gogs section")
	flag.Parse()

	cfg, err := ini.Load(configfile)
	if err != nil {
		return err
	}

	globalsection := cfg.Section("global")
	githubsection := cfg.Section("github")
	gogssection := cfg.Section("gogs")

	globalconfig.UserAgent = globalsection.Key("user_agent").String()
	globalconfig.RequestTimeout, err = globalsection.Key("request_timeout").Duration()
	if err != nil {
		return err
	}
	globalconfig.Threads, err = globalsection.Key("threads").Int()
	if err != nil {
		return err
	}

	githubconfig.PageNum, err = githubsection.Key("page_num").Int()
	if err != nil {
		return err
	}
	githubconfig.MaxPerPage, err = githubsection.Key("max_per_page").Int()
	if err != nil {
		return err
	}

	githubconfig.AuthUsername = githubsection.Key("auth_username").String()
	githubconfig.AuthPassword = githubsection.Key("auth_password").String()
	githubconfig.ContentType = githubsection.Key("content_type").String()

	gogsconfig.Username = gogssection.Key("username").String()
	gogsconfig.DestUsername = gogssection.Key("dest_username").String()
	gogsconfig.RepoURLTmpl = gogssection.Key("repo_url_tmpl").String()
	gogsconfig.OrgsURLTmpl = gogssection.Key("orgs_url_tmpl").String()
	gogsconfig.MigrateURL = gogssection.Key("migrate_url").String()
	gogsconfig.AuthToken = gogssection.Key("auth_token").String()
	gogsconfig.ContentType = gogssection.Key("content_type").String()
	gogsconfig.Mirror, err = gogssection.Key("mirror").Bool()
	if err != nil {
		return err
	}

	*config = Config{globalconfig: globalconfig,
		githubconfig: githubconfig,
		gogsconfig:   gogsconfig}

	return nil
}

// GetReposFromGitHub get starred repositories from github
func GetReposFromGitHub(config *Config) ([]GitHubRepo, error) {
	var repopartiallist []GitHubRepo
	var repofulllist []GitHubRepo

	fmt.Println("Getting GitHub starred repos")
	for num := 1; num <= config.githubconfig.PageNum; num++ {
		url := fmt.Sprintf("https://api.github.com/users/%s/starred?per_page=%d&page=%d", config.githubconfig.AuthUsername, config.githubconfig.MaxPerPage, num)
		fmt.Println(url)

		resp, err := InvokeGitHub(config, url)
		if err != nil {
			return nil, err
		}

		respbody, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			return nil, err
		}

		err = json.Unmarshal(respbody, &repopartiallist)
		if err != nil {
			return nil, err
		}

		for _, elem := range repopartiallist {
			repofulllist = append(repofulllist, elem)
		}
	}

	fmt.Println(fmt.Sprintf("%d repositories from Github fetched", len(repofulllist)))
	return repofulllist, nil
}

// InvokeGitHub ...
func InvokeGitHub(config *Config, url string) (*http.Response, error) {
	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		return nil, err
	}

	req.Header.Add("Content-Type", config.githubconfig.ContentType)
	req.Header.Set("User-Agent", config.globalconfig.UserAgent)
	req.SetBasicAuth(config.githubconfig.AuthUsername, config.githubconfig.AuthPassword)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}

	return resp, nil
}

// CheckGogsExistingRepo checks if there's an existing repository in gogs
func CheckGogsExistingRepo(config *Config, repo GitHubRepo) (bool, error) {
	var isexists bool

	gogsrepourl := fmt.Sprintf(config.gogsconfig.RepoURLTmpl, config.gogsconfig.DestUsername, repo.Name)

	req, err := http.NewRequest("GET", gogsrepourl, nil)
	req.Header.Set("Authorization", config.gogsconfig.AuthToken)
	req.Header.Set("User-Agent", config.globalconfig.UserAgent)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return false, err
	}

	if resp.StatusCode == 200 {
		isexists = true
	} else if resp.StatusCode == 404 {
		isexists = false
	} else {
		err = fmt.Errorf("Can't determine error, cancelling, error %d in gogs webservice", resp.StatusCode)
		return false, err
	}

	return isexists, nil
}

// GetGogsUserUID get the logued user identifier
func (config *Config) GetGogsUserUID() error {
	var gogsorg GogsOrg

	gogsrepourl := fmt.Sprintf(config.gogsconfig.OrgsURLTmpl, config.gogsconfig.DestUsername)

	req, err := http.NewRequest("GET", gogsrepourl, nil)
	if err != nil {
		return err
	}

	req.Header.Set("Authorization", config.gogsconfig.AuthToken)
	req.Header.Set("User-Agent", config.globalconfig.UserAgent)

	client := &http.Client{}
	resp, err := client.Do(req)
	if err != nil {
		return err
	}

	if resp.StatusCode != 200 {
		err = errors.New("Error invoking gogs webservice")
		return err
	}

	respbody, err := ioutil.ReadAll(resp.Body)

	err = json.Unmarshal(respbody, &gogsorg)
	if err != nil {
		err = errors.New("Failed to parse user ID from gogs webservice, check auth")
		return err
	}

	config.gogsconfig.UID = gogsorg.ID

	return nil
}

// RunMigration run threads for migration
func RunMigration(config *Config, repolist []GitHubRepo) {
	repochan := make(chan GitHubRepo)
	done := make(chan bool)

	var wg sync.WaitGroup
	for thr := range make([]int, config.globalconfig.Threads) {
		go MigrateReposToGogs(config, &wg, repochan, done, thr)
	}

	for _, repo := range repolist {
		repochan <- repo
	}
	close(repochan)
	<-done
	wg.Wait()
}

// MigrateReposToGogs migrates input repositories to gogs
func MigrateReposToGogs(config *Config, wg *sync.WaitGroup, jobs chan GitHubRepo, done chan bool, thr int) error {
	wg.Add(1)
	for {
		elem, more := <-jobs
		if more {
			client := &http.Client{}

			existingrepo, err := CheckGogsExistingRepo(config, elem)
			if err != nil {
				return err
			}
			if !existingrepo {
				jsondata := fmt.Sprintf(`{"uid" : %d, "repo_name" : "%s" , "mirror" : %v, "clone_addr" : "%s"}`, config.gogsconfig.UID, elem.Name, true, elem.CloneURL)

				req, err := http.NewRequest("POST", config.gogsconfig.MigrateURL, bytes.NewBufferString(jsondata))
				if err != nil {
					return err
				}

				req.Header.Add("Content-Type", config.gogsconfig.ContentType)
				req.Header.Set("User-Agent", config.globalconfig.UserAgent)
				req.Header.Set("Authorization", config.gogsconfig.AuthToken)

				client.Timeout = config.globalconfig.RequestTimeout

				fmt.Println(fmt.Sprintf("Migrating repo %s to gogs rest api", elem.Name))

				resp, err := client.Do(req)
				if err != nil {
					return err
				}

				if resp.StatusCode != 201 {
					err = fmt.Errorf("Error when migrating repo %s to gogs with status code %d on gogs webservice", elem.Name, resp.StatusCode)
					log.Println(err)
				}
			} else {
				fmt.Println(fmt.Sprintf("Not migrating, %s exists in gogs", elem.Name))
			}
		} else {
			fmt.Println(fmt.Sprintf("All repo migrated on thread num %d", thr))
			wg.Done()
			done <- true
			return nil
		}
	}
}

// Usage displays possible arguments
func Usage() {
	flag.PrintDefaults()
	os.Exit(1)
}