package cmd

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"syscall"
	"time"

	"git.ilapage.cn/OPC/chorus/admin/app/admin/router"
	"git.ilapage.cn/OPC/chorus/admin/app/chorus"
	"git.ilapage.cn/OPC/chorus/admin/common/database"
	common "git.ilapage.cn/OPC/chorus/admin/common/middleware"
	ext "git.ilapage.cn/OPC/chorus/admin/config"
	safehttp "git.ilapage.cn/OPC/chorus/internal/platform/http"
	"github.com/gin-gonic/gin"
	"github.com/go-admin-team/go-admin-core/config/source/file"
	"github.com/go-admin-team/go-admin-core/sdk"
	coreapi "github.com/go-admin-team/go-admin-core/sdk/api"
	coreconfig "github.com/go-admin-team/go-admin-core/sdk/config"
	"github.com/go-admin-team/go-admin-core/sdk/pkg"
	"github.com/spf13/cobra"
	"gorm.io/gorm"
)

var configPath string

var rootCmd = &cobra.Command{
	Use:          "chorus-admin",
	SilenceUsage: true,
}

var serverCmd = &cobra.Command{
	Use:   "server",
	Short: "Start the Chorus go-admin backend",
	PreRunE: func(cmd *cobra.Command, args []string) error {
		return setup(configPath)
	},
	RunE: func(cmd *cobra.Command, args []string) error {
		return serve()
	},
}

func init() {
	serverCmd.Flags().StringVarP(&configPath, "config", "c", "", "go-admin settings file")
	rootCmd.AddCommand(serverCmd)
}

func Execute() error {
	return rootCmd.Execute()
}

func setup(path string) error {
	if strings.TrimSpace(path) == "" {
		return errors.New("--config is required; use config/settings.example.yml as a starting point")
	}
	coreconfig.ExtendConfig = &ext.ExtConfig
	coreconfig.Setup(file.NewSource(file.WithPath(path)), database.Setup)
	serviceConfig, err := serviceConfigFromEnvironment(os.LookupEnv)
	if err != nil {
		return err
	}
	chorus.Configure(func(db *gorm.DB) (*chorus.Service, error) {
		return chorus.NewService(db, serviceConfig.config)
	})
	return nil
}

type configuredService struct {
	config chorus.Config
}

func serviceConfigFromEnvironment(lookup func(string) (string, bool)) (configuredService, error) {
	read := func(name string) string {
		value, _ := lookup(name)
		return strings.TrimSpace(value)
	}
	configured := configuredService{}
	allowRaw := read("CHORUS_ADMIN_ALLOW_CONNECTIVITY_PROBES")
	if allowRaw == "" || allowRaw == "0" {
		return configured, nil
	}
	if allowRaw != "1" {
		return configuredService{}, errors.New("CHORUS_ADMIN_ALLOW_CONNECTIVITY_PROBES must be 1 when set")
	}
	cooldown, err := positiveDuration(read("CHORUS_ADMIN_CONNECTIVITY_COOLDOWN_SECONDS"), time.Second)
	if err != nil {
		return configuredService{}, errors.New("CHORUS_ADMIN_CONNECTIVITY_COOLDOWN_SECONDS must be a positive integer")
	}
	timeout, err := positiveDuration(read("CHORUS_PROVIDER_HTTP_TIMEOUT_SECONDS"), time.Second)
	if err != nil {
		return configuredService{}, errors.New("CHORUS_PROVIDER_HTTP_TIMEOUT_SECONDS must be a positive integer")
	}
	maxResponse, err := positiveInt64(read("CHORUS_PROVIDER_MAX_RESPONSE_BYTES"))
	if err != nil {
		return configuredService{}, errors.New("CHORUS_PROVIDER_MAX_RESPONSE_BYTES must be a positive integer")
	}
	client, err := safehttp.New(safehttp.Config{Timeout: timeout, MaxRedirects: 3})
	if err != nil {
		return configuredService{}, errors.New("configure SSRF-safe connectivity client")
	}
	probe, err := chorus.NewLiveProbe(safehttp.NewProviderClient(client))
	if err != nil {
		return configuredService{}, errors.New("configure connectivity probe")
	}
	configured.config = chorus.Config{AllowConnectivityChecks: true, ConnectivityCooldown: cooldown, MaxResponseBytes: maxResponse, Probe: probe}
	return configured, nil
}

func positiveDuration(raw string, unit time.Duration) (time.Duration, error) {
	value, err := strconv.ParseInt(raw, 10, 64)
	if err != nil || value <= 0 {
		return 0, errors.New("invalid positive duration")
	}
	return time.Duration(value) * unit, nil
}

func positiveInt64(raw string) (int64, error) {
	value, err := strconv.ParseInt(raw, 10, 64)
	if err != nil || value <= 0 {
		return 0, errors.New("invalid positive integer")
	}
	return value, nil
}

func serve() error {
	if coreconfig.ApplicationConfig.Mode == pkg.ModeProd.String() {
		gin.SetMode(gin.ReleaseMode)
	}
	engine := gin.New()
	sdk.Runtime.SetEngine(engine)
	engine.Use(common.Sentinel()).Use(common.RequestId(pkg.TrafficKey)).Use(coreapi.SetRequestLogger)
	common.InitMiddleware(engine)
	router.InitRouter()

	server := &http.Server{
		Addr:              fmt.Sprintf("%s:%d", coreconfig.ApplicationConfig.Host, coreconfig.ApplicationConfig.Port),
		Handler:           engine,
		ReadHeaderTimeout: 5 * time.Second,
		ReadTimeout:       time.Duration(coreconfig.ApplicationConfig.ReadTimeout) * time.Second,
		WriteTimeout:      time.Duration(coreconfig.ApplicationConfig.WriterTimeout) * time.Second,
		IdleTimeout:       60 * time.Second,
	}
	shutdown, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	result := make(chan error, 1)
	go func() { result <- server.ListenAndServe() }()
	select {
	case <-shutdown.Done():
		ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
		defer cancel()
		return server.Shutdown(ctx)
	case err := <-result:
		if errors.Is(err, http.ErrServerClosed) {
			return nil
		}
		return err
	}
}