package main

import (
	"code.gitea.io/sdk/gitea"
	b64 "encoding/base64"
	"encoding/json"
	"fmt"
	"github.com/caarlos0/env/v7"
	consul "github.com/hashicorp/consul/api"
	nomad "github.com/hashicorp/nomad/api"
	"golang.org/x/exp/slices"
	"io"
	"log"
	"net/http"
	"strings"
)

type GitUser struct {
	Name     string `json:"name"`
	Email    string `json:"email"`
	Username string `json:username"`
}

type GiteaCommit struct {
	Id        string  `json:"id"`
	Message   string  `json:"message"`
	Url       string  `json:"string"`
	Author    GitUser `json:"author"`
	Committer GitUser `json:"committer"`
	Timestamp string  `json:"timestamp"`
}

type GiteaAccount struct {
	Id        int64  `json:"id"`
	Login     string `json:"login"`
	FullName  string `json:"full_name"`
	Email     string `json:"email"`
	AvatarUrl string `json:"avatar_url"`
	Username  string `json:"username"`
}

type GiteaRepository struct {
	Id              int64        `json:"id"`
	Owner           GiteaAccount `json:"owner"`
	Name            string       `json:"name"`
	FullName        string       `json:"full_name"`
	Description     string       `json:"description"`
	Private         bool         `json:"private"`
	Fork            bool         `json:"private"`
	HtmlUrl         string       `json:"html_url"`
	SshUrl          string       `json:"ssh_url"`
	CloneUrl        string       `json:"clone_url"`
	Website         string       `json:"website"`
	StarsCount      int64        `json:"stars_count"`
	ForksCount      int64        `json:"forks_count"`
	WatchersCount   int64        `json:"watchers_count"`
	OpenIssuesCount int64        `json:"open_issues_count"`
	DefaultBranch   string       `json:"default_branch"`
	CreatedAt       string       `json:"created_at"`
	UpdatedAt       string       `json:"updated_at"`
}

type GiteaNotification struct {
	Secret     string          `json:"secret"`
	Ref        string          `json:"ref"`
	Before     string          `json:"before"`
	After      string          `json:"after"`
	CompareUrl string          `json:"compare_url"`
	Commits    []GiteaCommit   `json:"commits"`
	Repository GiteaRepository `json:"repository"`
	Pusher     GiteaAccount    `json:"pusher"`
	Sender     GiteaAccount    `json:"sender"`
}

type SecretHook struct {
	Token string `json:"token"`
}

type SecretGitea struct {
	Url   string `json:"url"`
	Token string `json:"token"`
}

type SecretTrusted struct {
	Senders []string `json:"senders"`
}

type ConsulSecret struct {
	Hook    SecretHook    `json:"hook"`
	Gitea   SecretGitea   `json:"gitea"`
	Trusted SecretTrusted `json:"trusted"`
	Inject  string        `json:"inject"`
}

func nomadToGiteaStatus(summary *nomad.TaskGroupSummary) gitea.StatusState {
	if summary.Failed > 0 {
		return gitea.StatusError
	}
	if summary.Lost > 0 || summary.Unknown > 0 {
		return gitea.StatusFailure
	}
	if summary.Queued > 0 || summary.Starting > 0 || summary.Running > 0 {
		return gitea.StatusPending
	}
	if summary.Complete > 0 {
		return gitea.StatusSuccess
	}
	// When the job is just started, all the counters are = 0.
	return gitea.StatusPending
}

func notifSummary(notification *GiteaNotification) string {
	return fmt.Sprintf("%s/%s:%s", notification.Repository.Owner.Username, notification.Repository.Name, notification.After)
}

func lifecycle(notification *GiteaNotification, dispatch *nomad.JobDispatchResponse, giteaCreds *SecretGitea) {
	notifInfo := notifSummary(notification)

	log.Printf("[lifecycle] Commit to build: %s, Gitea URL: %s\n", notifInfo, giteaCreds.Url)
	// init Gitea
	forge, err := gitea.NewClient(giteaCreds.Url, gitea.SetToken(giteaCreds.Token))
	if err != nil {
		log.Printf("Unable to create gitea client for %s: %+v\n", notifInfo, err)
		return
	}

	// get job's deployment
	jobs := NomadClient.Jobs()
	queryOpt := nomad.QueryOptions{
		AllowStale: true,
	}

	safeguard := 1000
	for ; safeguard > 0; safeguard-- {
		// Blocking fetch on deployment info
		job, meta, err := jobs.Summary(dispatch.DispatchedJobID, &queryOpt)
		if err != nil {
			log.Printf("[lifecycle] can't fetch job for %s: %+v\n", notifInfo, err)
			break
		}
		queryOpt.WaitIndex = meta.LastIndex

		summary, ok := job.Summary["runner"]
		if !ok {
			log.Printf("[lifecycle] Job %s for %s must contain a 'runner' task\n", job.JobID, notifInfo)
			break
		}
		log.Printf("[lifecycle] Task status for job %s on %s: %+v\n", job.JobID, notifInfo, summary)

		// Compute new job state
		state := nomadToGiteaStatus(&summary)

		// Try updating Gitea commit status
		_, _, err = forge.CreateStatus(
			notification.Repository.Owner.Username,
			notification.Repository.Name,
			notification.After,
			gitea.CreateStatusOption{
				State:       state,
				TargetURL:   GlobalConfig.AlbatrosURL + "/build?log=stderr&job=" + dispatch.DispatchedJobID,
				Description: "build",
				Context:     "Albatros",
			})

		if err != nil {
			log.Printf("[lifecycle] can't update gitea repo %s for job %s: %+v\n", notifInfo, job.JobID, err)
		}

		// Continue the loop only if the job is pending
		if state != gitea.StatusPending {
			log.Printf("Job %s for %s terminated with status %s\n", job.JobID, notifInfo, state)
			break
		}
	}

	if safeguard == 0 {
		// To avoid dangerous infinite loops, we put an upperbound here
		// of 1k refresh here. Reaching this limit will allow us to know
		// that something did not work as expected...
		log.Printf("!!! [lifecycle] we refreshed 1k times the job of %s and it's still running, giving up...\n", notifInfo)
	}
}

func hook(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "Hook only support POST requests", http.StatusBadRequest)
	}

	q := r.URL.Query()
	maybeToken, ok := q["token"]
	if !ok || len(maybeToken) < 1 {
		http.Error(w, "Missing query parameter 'token'. Try adding '?token=xxx'", http.StatusBadRequest)
		return
	}
	token := maybeToken[0]
	flavor := "default"

	var notification GiteaNotification
	dec := json.NewDecoder(r.Body)
	if err := dec.Decode(&notification); err != nil {
		http.Error(w, "Can't parse your request JSON", http.StatusBadRequest)
		return
	}
	notifInfo := notifSummary(&notification)

	log.Printf("Received gitea notification for %s\n", notifInfo)

	// Fetch our repo descriptor
	kv := ConsulClient.KV()
	encodedRepoUrl := b64.StdEncoding.EncodeToString([]byte(notification.Repository.CloneUrl))
	key := "albatros/" + encodedRepoUrl
	log.Printf("Fetching key %s for %s\n", key, notifInfo)
	pair, _, err := kv.Get(key, nil)
	if err != nil {
		http.Error(w, "Can't fetch the repo descriptor in Consul", http.StatusInternalServerError)
		return
	}
	if pair == nil || pair.Value == nil {
		http.Error(w, "You must declare %s in Consul in order to build it", http.StatusForbidden)
		return
	}
	// Parse our repo descriptor
	var repoDesc ConsulSecret
	if err = json.Unmarshal(pair.Value, &repoDesc); err != nil {
		http.Error(w, "Can't decode your Consul configuration for this repo", http.StatusInternalServerError)
		return
	}
	// Check token
	if repoDesc.Hook.Token != token {
		http.Error(w, "Your albatros token does not match the one declared in Consul", http.StatusForbidden)
		return
	}

	// Build job parameters for Nomad
	meta := map[string]string{
		"REPO_URL": notification.Repository.CloneUrl,
		"COMMIT":   notification.After,
		"FLAVOR":   flavor,
		// @FIXME: this code is not correct, this is a hack
		"BRANCH": strings.ReplaceAll(notification.Ref, "refs/heads/", ""),
	}

	// Check sender
	payload := []byte{}
	if slices.Contains(repoDesc.Trusted.Senders, notification.Sender.Username) {
		log.Printf("Trusted build of %s as %s in the list of allowed senders, inject secrets\n", notifInfo, notification.Sender.Username)
		// Write payload
		payload = []byte(repoDesc.Inject)
	}

	jobs := NomadClient.Jobs()
	dres, _, err := jobs.Dispatch("builder", meta, payload, "albatros", &nomad.WriteOptions{})
	if err != nil {
		http.Error(w, "Can't submit your job to Nomad", http.StatusInternalServerError)
	}
	log.Printf("Created job %s for %s\n", dres.DispatchedJobID, notifInfo)

	// Start a lifecycle observer to update gitea status
	go lifecycle(&notification, dres, &repoDesc.Gitea)

	io.WriteString(w, dres.DispatchedJobID)
}

func build(w http.ResponseWriter, r *http.Request) {
	q := r.URL.Query()
	jobID, ok := q["job"]
	if !ok || len(jobID) < 1 {
		http.Error(w, "Missing query parameter 'job'. Try adding '?job=xxx'", http.StatusBadRequest)
		return
	}

	logType, ok := q["log"]
	log.Printf("Follow logs for %s\n", jobID)
	if !ok || len(logType) < 1 || !(logType[0] == "stdout" || logType[0] == "stderr") {
		http.Error(w, "Missing or wrong query parameter 'log'.\nTry adding '?log=stdout' or '?log=stderr'", http.StatusBadRequest)
		return
	}
	logFilter := logType[0]

	jobs := NomadClient.Jobs()
	allocList, _, err := jobs.Allocations(jobID[0], true, &nomad.QueryOptions{})
	if err != nil {
		http.Error(w, "Unable to fetch your job on Nomad. Might be garbage collected.", http.StatusInternalServerError)
		return
	}
	if len(allocList) < 1 {
		http.Error(w, "Job does not contain at least 1 allocation, can't display logs. Job might be garbage collected. ", http.StatusNotFound)
		return
	}

	myAllocStub := allocList[0]

	allocations := NomadClient.Allocations()
	myAlloc, _, err := allocations.Info(myAllocStub.ID, &nomad.QueryOptions{})
	if err != nil {
		http.Error(w, "Allocation does not exist anymore. Allocation might be garbage collected", http.StatusNotFound)
		return
	}
	log.Printf("Selected alloc %s for job %s\n", myAlloc.ID, jobID)

	allocFS := NomadClient.AllocFS()
	scancel := make(chan struct{})
	sframe, serr := allocFS.Logs(myAlloc, true, "runner", logFilter, "start", 0, scancel, &nomad.QueryOptions{})

	// stream logs to client's browser
build_loop:
	for {
		select {
		case <-r.Context().Done():
			// client disconnect, cleaning
			break build_loop
		case nomadErr := <-serr:
			// an error occured in nomad, inform user and clean
			_, _ = io.WriteString(w, fmt.Sprintf("\nBroken stream: %+v\n", nomadErr))
			break build_loop
		case chunk := <-sframe:
			// we get some data from nomad, send it to the client
			for i := 0; i < len(chunk.Data); {
				written, err := w.Write(chunk.Data[i:])
				w.(http.Flusher).Flush() // flush the buffer to send it right now
				i += written
				if err == io.EOF {
					_, _ = io.WriteString(w, "End of file :-)")
					break build_loop
				} else if err != nil {
					_, _ = io.WriteString(w, fmt.Sprintf("\nBroken stream: %+v\n", err))
					break build_loop
				}
			}
		}
	}

	log.Printf("Connection closed, cleaning listeners for %s\n", jobID)
	scancel <- struct{}{}
}

var NomadClient *nomad.Client
var ConsulClient *consul.Client

type config struct {
	AlbatrosURL string `env:"ALBATROS_URL,required"`
	// @TODO get nomad config from env
	// @TODO get consul config from env
}

var GlobalConfig config

func main() {
	var err error

	// init config
	if err = env.Parse(&GlobalConfig); err != nil {
		log.Fatal(fmt.Sprintf("unable to parse config, error: %+v\n", err))
		return
	}
	log.Printf("Albatros public URL: %s\n", GlobalConfig.AlbatrosURL)

	// init nomad
	nomadConfig := nomad.DefaultConfig()
	nomadConfig.Namespace = "ci"
	NomadClient, err = nomad.NewClient(nomadConfig)
	if err != nil {
		log.Fatal("Unable to connect to Nomad, check your config and setup")
		return
	}

	// init consul
	consulConfig := consul.DefaultConfig()
	ConsulClient, err = consul.NewClient(consulConfig)
	if err != nil {
		log.Fatal("Unable to connect to Consul, check your config and setup")
		return
	}

	// init webserver
	http.HandleFunc("/hook", hook)
	http.HandleFunc("/build", build)

	// launch
	log.Println("Listen on :8080")
	if err = http.ListenAndServe(":8080", nil); err != nil {
		log.Fatal("Can't start HTTP server")
	}
}