// Copyright 2023 Woodpecker Authors
// Copyright 2018 Drone.IO Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"net/http"
	"os"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/log"
	"github.com/tevino/abool"
	"github.com/urfave/cli/v2"
	"google.golang.org/grpc"
	"google.golang.org/grpc/codes"
	grpccredentials "google.golang.org/grpc/credentials"
	"google.golang.org/grpc/credentials/insecure"
	"google.golang.org/grpc/keepalive"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/status"

	"github.com/woodpecker-ci/woodpecker/agent"
	agentRpc "github.com/woodpecker-ci/woodpecker/agent/rpc"
	"github.com/woodpecker-ci/woodpecker/pipeline/backend"
	"github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
	"github.com/woodpecker-ci/woodpecker/pipeline/rpc"
	"github.com/woodpecker-ci/woodpecker/shared/utils"
	"github.com/woodpecker-ci/woodpecker/version"
)

func run(c *cli.Context) error {
	agentIDConfigPath := c.String("agent-id-config-path")
	hostname := c.String("hostname")
	if len(hostname) == 0 {
		hostname, _ = os.Hostname()
	}

	platform := runtime.GOOS + "/" + runtime.GOARCH

	if c.Bool("pretty") {
		log.Logger = log.Output(
			zerolog.ConsoleWriter{
				Out:     os.Stderr,
				NoColor: c.Bool("nocolor"),
			},
		)
	}

	zerolog.SetGlobalLevel(zerolog.InfoLevel)
	if c.IsSet("log-level") {
		logLevelFlag := c.String("log-level")
		lvl, err := zerolog.ParseLevel(logLevelFlag)
		if err != nil {
			log.Fatal().Msgf("unknown logging level: %s", logLevelFlag)
		}
		zerolog.SetGlobalLevel(lvl)
	}
	if zerolog.GlobalLevel() <= zerolog.DebugLevel {
		log.Logger = log.With().Caller().Logger()
	}

	counter.Polling = c.Int("max-workflows")
	counter.Running = 0

	if c.Bool("healthcheck") {
		go func() {
			if err := http.ListenAndServe(c.String("healthcheck-addr"), nil); err != nil {
				log.Error().Msgf("cannot listen on address %s: %v", c.String("healthcheck-addr"), err)
			}
		}()
	}

	var transport grpc.DialOption
	if c.Bool("grpc-secure") {
		transport = grpc.WithTransportCredentials(grpccredentials.NewTLS(&tls.Config{InsecureSkipVerify: c.Bool("skip-insecure-grpc")}))
	} else {
		transport = grpc.WithTransportCredentials(insecure.NewCredentials())
	}

	authConn, err := grpc.Dial(
		c.String("server"),
		transport,
		grpc.WithKeepaliveParams(keepalive.ClientParameters{
			Time:    c.Duration("grpc-keepalive-time"),
			Timeout: c.Duration("grpc-keepalive-timeout"),
		}),
	)
	if err != nil {
		return err
	}
	defer authConn.Close()

	agentID := readAgentID(agentIDConfigPath)
	agentToken := c.String("grpc-token")
	authClient := agentRpc.NewAuthGrpcClient(authConn, agentToken, agentID)
	authInterceptor, err := agentRpc.NewAuthInterceptor(authClient, 30*time.Minute)
	if err != nil {
		return err
	}

	conn, err := grpc.Dial(
		c.String("server"),
		transport,
		grpc.WithKeepaliveParams(keepalive.ClientParameters{
			Time:    c.Duration("grpc-keepalive-time"),
			Timeout: c.Duration("grpc-keepalive-timeout"),
		}),
		grpc.WithUnaryInterceptor(authInterceptor.Unary()),
		grpc.WithStreamInterceptor(authInterceptor.Stream()),
	)
	if err != nil {
		return err
	}
	defer conn.Close()

	client := agentRpc.NewGrpcClient(conn)

	sigterm := abool.New()
	ctx := metadata.NewOutgoingContext(
		context.Background(),
		metadata.Pairs("hostname", hostname),
	)
	ctx = utils.WithContextSigtermCallback(ctx, func() {
		println("ctrl+c received, terminating process")
		sigterm.Set()
	})

	// check if grpc server version is compatible with agent
	grpcServerVersion, err := client.Version(ctx)
	if err != nil {
		log.Error().Err(err).Msg("could not get grpc server version")
		return err
	}
	if grpcServerVersion.GrpcVersion != agentRpc.ClientGrpcVersion {
		err := errors.New("GRPC version mismatch")
		log.Error().Err(err).Msgf("Server version %s does report grpc version %d but we only understand %d",
			grpcServerVersion.ServerVersion,
			grpcServerVersion.GrpcVersion,
			agentRpc.ClientGrpcVersion)
		return err
	}

	backendCtx := context.WithValue(ctx, types.CliContext, c)
	backend.Init(backendCtx)

	var wg sync.WaitGroup
	parallel := c.Int("max-workflows")
	wg.Add(parallel)

	// new engine
	engine, err := backend.FindEngine(backendCtx, c.String("backend-engine"))
	if err != nil {
		log.Error().Err(err).Msgf("cannot find backend engine '%s'", c.String("backend-engine"))
		return err
	}

	agentID, err = client.RegisterAgent(ctx, platform, engine.Name(), version.String(), parallel)
	if err != nil {
		return err
	}

	writeAgentID(agentID, agentIDConfigPath)

	labels := map[string]string{
		"hostname": hostname,
		"platform": platform,
		"backend":  engine.Name(),
		"repo":     "*", // allow all repos by default
	}

	if err := stringSliceAddToMap(c.StringSlice("filter"), labels); err != nil {
		return err
	}

	filter := rpc.Filter{
		Labels: labels,
	}

	log.Debug().Msgf("Agent registered with ID %d", agentID)

	go func() {
		for {
			if sigterm.IsSet() {
				return
			}

			err := client.ReportHealth(ctx)
			if err != nil {
				log.Err(err).Msgf("Failed to report health")
				return
			}

			<-time.After(time.Second * 10)
		}
	}()

	for i := 0; i < parallel; i++ {
		go func() {
			defer wg.Done()

			// load engine (e.g. init api client)
			err = engine.Load(backendCtx)
			if err != nil {
				log.Error().Err(err).Msg("cannot load backend engine")
				return
			}

			r := agent.NewRunner(client, filter, hostname, counter, &engine)

			log.Debug().Msgf("loaded %s backend engine", engine.Name())

			for {
				if sigterm.IsSet() {
					return
				}

				log.Debug().Msg("polling new steps")
				if err := r.Run(ctx); err != nil {
					log.Error().Err(err).Msg("pipeline done with error")
					return
				}
			}
		}()
	}

	log.Info().Msgf(
		"Starting Woodpecker agent with version '%s' and backend '%s' using platform '%s' running up to %d pipelines in parallel",
		version.String(), engine.Name(), platform, parallel)

	wg.Wait()
	return nil
}

func runWithRetry(context *cli.Context) error {
	retryCount := context.Int("connect-retry-count")
	retryDelay := context.Duration("connect-retry-delay")
	var err error
	for i := 0; i < retryCount; i++ {
		if err = run(context); status.Code(err) == codes.Unavailable {
			log.Warn().Err(err).Msg(fmt.Sprintf("cannot connect to server, retrying in %v", retryDelay))
			time.Sleep(retryDelay)
		} else {
			break
		}
	}
	return err
}

func stringSliceAddToMap(sl []string, m map[string]string) error {
	if m == nil {
		m = make(map[string]string)
	}
	for _, v := range sl {
		parts := strings.SplitN(v, "=", 2)
		switch len(parts) {
		case 2:
			m[parts[0]] = parts[1]
		case 1:
			return fmt.Errorf("key '%s' does not have a value assigned", parts[0])
		default:
			return fmt.Errorf("empty string in slice")
		}
	}
	return nil
}

func readAgentID(agentIDConfigPath string) int64 {
	const defaultAgentIDValue = int64(-1)

	rawAgentID, fileErr := os.ReadFile(agentIDConfigPath)
	if fileErr != nil {
		log.Debug().Err(fileErr).Msgf("could not open agent-id config file from %s", agentIDConfigPath)
		return defaultAgentIDValue
	}

	strAgentID := strings.TrimSpace(string(rawAgentID))
	agentID, parseErr := strconv.ParseInt(strAgentID, 10, 64)
	if parseErr != nil {
		log.Warn().Err(parseErr).Msg("could not parse agent-id config file content to int64")
		return defaultAgentIDValue
	}

	return agentID
}

func writeAgentID(agentID int64, agentIDConfigPath string) {
	currentAgentID := readAgentID(agentIDConfigPath)

	if currentAgentID != agentID {
		err := os.WriteFile(agentIDConfigPath, []byte(strconv.FormatInt(agentID, 10)+"\n"), 0o644)
		if err != nil {
			log.Warn().Err(err).Msgf("could not write agent-id config file to %s", agentIDConfigPath)
		}
	}
}