/*
Copyright 2020, 2022 The Flux authors

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 loadtester

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"time"

	flaggerv1 "github.com/fluxcd/flagger/pkg/apis/flagger/v1beta1"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"go.uber.org/zap"
)

// ListenAndServe starts a web server and waits for SIGTERM
func ListenAndServe(port string, timeout time.Duration, logger *zap.SugaredLogger, taskRunner *TaskRunner, gate *GateStorage, authorizer *Authorizer, stopCh <-chan struct{}) {
	mux := http.DefaultServeMux
	mux.Handle("/metrics", promhttp.Handler())
	mux.HandleFunc("/healthz", HandleHealthz)
	mux.HandleFunc("/gate/approve", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		w.Write([]byte("OK"))
	})
	mux.HandleFunc("/gate/halt", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusForbidden)
		w.Write([]byte("Forbidden"))
	})
	mux.HandleFunc("/gate/check", func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		canary := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, canary)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(canary) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		canaryName := fmt.Sprintf("%s.%s", canary.Name, canary.Namespace)
		approved := gate.isOpen(canaryName)
		if approved {
			w.WriteHeader(http.StatusOK)
			w.Write([]byte("Approved"))
		} else {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
		}

		logger.Infof("%s gate check: approved %v", canaryName, approved)
	})

	mux.HandleFunc("/gate/open", func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		canary := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, canary)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(canary) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		canaryName := fmt.Sprintf("%s.%s", canary.Name, canary.Namespace)
		gate.open(canaryName)

		w.WriteHeader(http.StatusAccepted)

		logger.Infof("%s gate opened", canaryName)
	})

	mux.HandleFunc("/gate/close", func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		canary := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, canary)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(canary) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		canaryName := fmt.Sprintf("%s.%s", canary.Name, canary.Namespace)
		gate.close(canaryName)

		w.WriteHeader(http.StatusAccepted)

		logger.Infof("%s gate closed", canaryName)
	})

	mux.HandleFunc("/rollback/check", func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		canary := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, canary)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(canary) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		canaryName := fmt.Sprintf("rollback.%s.%s", canary.Name, canary.Namespace)
		approved := gate.isOpen(canaryName)
		if approved {
			w.WriteHeader(http.StatusOK)
			w.Write([]byte("Approved"))
		} else {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
		}

		logger.Infof("%s rollback check: approved %v", canaryName, approved)
	})
	mux.HandleFunc("/rollback/open", func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		canary := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, canary)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(canary) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		canaryName := fmt.Sprintf("rollback.%s.%s", canary.Name, canary.Namespace)
		gate.open(canaryName)

		w.WriteHeader(http.StatusAccepted)

		logger.Infof("%s rollback opened", canaryName)
	})
	mux.HandleFunc("/rollback/close", func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		canary := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, canary)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(canary) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		canaryName := fmt.Sprintf("rollback.%s.%s", canary.Name, canary.Namespace)
		gate.close(canaryName)

		w.WriteHeader(http.StatusAccepted)

		logger.Infof("%s rollback closed", canaryName)
	})

	mux.HandleFunc("/", HandleNewTask(logger, taskRunner, authorizer))
	srv := &http.Server{
		Addr:    ":" + port,
		Handler: mux,
	}

	// run server in background
	go func() {
		if err := srv.ListenAndServe(); err != http.ErrServerClosed {
			logger.Fatalf("HTTP server crashed %v", err)
		}
	}()

	// wait for SIGTERM or SIGINT
	<-stopCh
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()

	if err := srv.Shutdown(ctx); err != nil {
		logger.Errorf("HTTP server graceful shutdown failed %v", err)
	} else {
		logger.Info("HTTP server stopped")
	}
}

// HandleHealthz handles heath check requests
func HandleHealthz(w http.ResponseWriter, r *http.Request) {
	w.WriteHeader(http.StatusOK)
	w.Write([]byte("OK"))
}

// HandleNewTask handles task creation requests
func HandleNewTask(logger *zap.SugaredLogger, taskRunner TaskRunnerInterface, authorizer *Authorizer) func(w http.ResponseWriter, r *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		body, err := io.ReadAll(r.Body)
		if err != nil {
			logger.Error("reading the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		payload := &flaggerv1.CanaryWebhookPayload{}
		err = json.Unmarshal(body, payload)
		if err != nil {
			logger.Error("decoding the request body failed", zap.Error(err))
			w.WriteHeader(http.StatusBadRequest)
			return
		}

		if !authorizer.Authorize(payload) {
			w.WriteHeader(http.StatusForbidden)
			w.Write([]byte("Forbidden"))
			return
		}

		if len(payload.Metadata) > 0 {
			metadata := payload.Metadata
			var typ, ok = metadata["type"]
			if !ok {
				typ = TaskTypeShell
			}

			rtnCmdOutput := false
			if rtn, ok := metadata["returnCmdOutput"]; ok {
				rtnCmdOutput, err = strconv.ParseBool(rtn)
			}

			// run bash command (blocking task)
			if typ == TaskTypeBash {
				logger.With("canary", payload.Name).Infof("bash command %s", payload.Metadata["cmd"])

				bashTask := BashTask{
					command:      payload.Metadata["cmd"],
					logCmdOutput: true,
					TaskBase: TaskBase{
						canary: fmt.Sprintf("%s.%s", payload.Name, payload.Namespace),
						logger: logger,
					},
				}

				ctx, cancel := context.WithTimeout(context.Background(), taskRunner.Timeout())
				defer cancel()

				result, err := bashTask.Run(ctx)
				if !result.ok {
					w.WriteHeader(http.StatusInternalServerError)
					w.Write([]byte(err.Error()))
					return
				}

				w.WriteHeader(http.StatusOK)
				if rtnCmdOutput {
					w.Write(result.out)
				}
				return
			}

			// run helmv3 command (blocking task)
			if typ == TaskTypeHelmv3 || typ == TaskTypeHelm {
				helm := HelmTaskv3{
					command:      payload.Metadata["cmd"],
					logCmdOutput: true,
					TaskBase: TaskBase{
						canary: fmt.Sprintf("%s.%s", payload.Name, payload.Namespace),
						logger: logger,
					},
				}

				ctx, cancel := context.WithTimeout(context.Background(), taskRunner.Timeout())
				defer cancel()

				result, err := helm.Run(ctx)
				if !result.ok {
					w.WriteHeader(http.StatusInternalServerError)
					w.Write([]byte(err.Error()))
					return
				}

				w.WriteHeader(http.StatusOK)
				if rtnCmdOutput {
					w.Write(result.out)
				}
				return
			}

			// run concord job (blocking task)
			if typ == TaskTypeConcord {
				concord, err := NewConcordTask(payload.Metadata, fmt.Sprintf("%s.%s", payload.Name, payload.Namespace), logger)

				if err != nil {
					logger.With("canary", payload.Name).Errorf("concord task init error: %s", err)
					w.WriteHeader(http.StatusInternalServerError)
					w.Write([]byte(err.Error()))
					return
				}

				ctx, cancel := context.WithTimeout(context.Background(), taskRunner.Timeout())
				defer cancel()

				result, err := concord.Run(ctx)
				if !result.ok {
					if err != nil {
						logger.With("canary", payload.Name).Errorf("concord task error: %s", err)
					}
					w.WriteHeader(http.StatusInternalServerError)
					w.Write([]byte(err.Error()))
					return
				}

				w.WriteHeader(http.StatusOK)
				if rtnCmdOutput {
					w.Write(result.out)
				}
				return
			}

			taskFactory, ok := GetTaskFactory(typ)
			if !ok {
				w.WriteHeader(http.StatusBadRequest)
				w.Write([]byte(fmt.Sprintf("unknown task type %s", typ)))
				return
			}
			canary := fmt.Sprintf("%s.%s", payload.Name, payload.Namespace)
			task, err := taskFactory(metadata, canary, logger)
			if err != nil {
				w.WriteHeader(http.StatusBadRequest)
				w.Write([]byte(err.Error()))
				return
			}
			taskRunner.Add(task)
		} else {
			w.WriteHeader(http.StatusBadRequest)
			w.Write([]byte("metadata not found in payload"))
			return
		}

		w.WriteHeader(http.StatusAccepted)
	}
}