// 本包是 yms-daemon 的入口，根据可执行文件名决定运行角色：
// 当二进制名为 ymsd 时作为守护进程服务端长期运行，否则作为 ymsctl 命令行客户端处理用户命令。
package main

import (
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"syscall"
	"time"

	"yms-daemon/internal/backendupdate"
	"yms-daemon/internal/containerengine"
	"yms-daemon/internal/daemonapi"
	"yms-daemon/internal/daemonclient"
	"yms-daemon/internal/daemonserver"
	"yms-daemon/internal/deploymentconfig"
	"yms-daemon/internal/filestore"
	"yms-daemon/internal/hostnginx"
	"yms-daemon/internal/logging"
	"yms-daemon/internal/processlock"
	"yms-daemon/internal/runtimepaths"
	"yms-daemon/internal/systemd"
	"yms-daemon/internal/transaction"
)

// serviceBackend 当前命令行客户端与守护进程唯一支持的目标服务名。
const serviceBackend = "backend"

// main 进程入口，负责根据可执行文件名分流到守护进程服务端或命令行客户端。
// 它先建立可被 os.Interrupt 与 SIGTERM 中断的上下文，再判断二进制名是否为 ymsd：
// 是则校验不接受任何参数并运行 runServe，否则把剩余参数交给 run 处理并以返回码退出。
func main() {
	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer cancel()
	if filepath.Base(os.Args[0]) == "ymsd" {
		if len(os.Args) != 1 {
			fmt.Fprintln(os.Stderr, "ymsd does not accept arguments")
			os.Exit(2)
		}
		if err := runServe(ctx); err != nil {
			fmt.Fprintln(os.Stderr, "ymsd failed:", err)
			os.Exit(1)
		}
		return
	}
	os.Exit(run(ctx, os.Args[1:], os.Stdout, os.Stderr))
}

// run 解析并执行命令行客户端的一个子命令，返回进程退出码。
// arguments 去除程序名后的命令行参数，stdout 与 stderr 分别接收正常输出与错误输出。
// 它支持 update、list、restart、help 子命令；无参数或未知命令时向 stderr 输出用法并返回 2，
// 命令执行失败返回 1，成功返回 0。
func run(ctx context.Context, arguments []string, stdout io.Writer, stderr io.Writer) int {
	if len(arguments) == 0 {
		writeUsage(stderr)
		return 2
	}
	switch arguments[0] {
	case "update":
		request, err := parseUpdateArgs(arguments[1:], stderr)
		if err != nil {
			fmt.Fprintln(stderr, err)
			return 2
		}
		var progress func(daemonapi.Response)
		if !request.quite {
			progress = func(event daemonapi.Response) {
				writeUpdateProgress(stdout, event)
			}
		}
		var response daemonapi.Response
		if request.inputType == daemonapi.InputTypeContainerImage {
			response, err = daemonclient.UpdateContainerImage(ctx, runtimepaths.Socket, request.service, request.imageReference, request.startLog, progress)
		} else {
			response, err = daemonclient.Update(ctx, runtimepaths.Socket, request.service, request.inputType, request.file, progress)
		}
		if err != nil {
			if response.TransactionID != "" {
				fmt.Fprintf(stderr, "transaction=%s state=%s error=%v\n", response.TransactionID, response.State, err)
			} else {
				fmt.Fprintln(stderr, "ymsctl update failed:", err)
			}
			return 1
		}
		if !request.quite {
			fmt.Fprintf(stdout, "transaction=%s state=%s\n", response.TransactionID, response.State)
		}
		return 0
	case "list":
		if err := runList(ctx, arguments[1:], stdout, stderr); err != nil {
			fmt.Fprintln(stderr, "ymsctl list failed:", err)
			return 1
		}
		return 0
	case "restart":
		request, err := parseRestartArgs(arguments[1:], stderr)
		if err != nil {
			fmt.Fprintln(stderr, err)
			return 2
		}
		var progress func(daemonapi.Response)
		if !request.quite {
			progress = func(event daemonapi.Response) {
				writeUpdateProgress(stdout, event)
			}
		}
		response, err := daemonclient.Restart(ctx, runtimepaths.Socket, request.service, progress)
		if err != nil {
			if response.TransactionID != "" {
				fmt.Fprintf(stderr, "transaction=%s state=%s error=%v\n", response.TransactionID, response.State, err)
			} else {
				fmt.Fprintln(stderr, "ymsctl restart failed:", err)
			}
			return 1
		}
		if !request.quite {
			fmt.Fprintf(stdout, "transaction=%s state=%s\n", response.TransactionID, response.State)
		}
		return 0
	case "help", "-h", "--help":
		writeUsage(stdout)
		return 0
	default:
		fmt.Fprintf(stderr, "unknown command: %s\n", arguments[0])
		writeUsage(stderr)
		return 2
	}
}

// updateArguments 保存 update 子命令解析后的参数。
type updateArguments struct {
	// service 目标服务名，当前仅接受 backend。
	service string
	// inputType 更新输入类型，由 -f 或 --native-jar 推导得到。
	inputType string
	// file 本地制品的绝对路径，容器镜像输入时为空。
	file string
	// imageReference 容器镜像引用，仅在 --container-image 输入时非空。
	imageReference string
	// quite 为真时抑制进度与成功结果的输出。
	quite bool
	// startLog 为真时在容器更新完成后输出启动日志。
	startLog bool
}

// restartArguments 保存 restart 子命令解析后的参数。
type restartArguments struct {
	// service 目标服务名，当前仅接受 backend。
	service string
	// quite 为真时抑制进度与成功结果的输出。
	quite bool
}

// parseUpdateArgs 解析 update 子命令的 flag 参数并做业务校验。
// 它要求 --service 必须为 backend，-f、--native-jar、--container-image 三者必须且只能提供一个；
// 对文件类输入会解析为绝对路径并校验其为非符号链接的普通文件，容器镜像输入不允许附带 --no-start-log。
// 校验失败时向 output 写入原因并返回 error。
func parseUpdateArgs(arguments []string, output io.Writer) (updateArguments, error) {
	flags := flag.NewFlagSet("update", flag.ContinueOnError)
	flags.SetOutput(output)
	service := flags.String("service", "", "service to update")
	file := flags.String("f", "", "repack ZIP path")
	nativeJAR := flags.String("native-jar", "", "direct native backend JAR path")
	containerImage := flags.String("container-image", "", "development backend container image reference")
	quite := flags.Bool("quite", false, "suppress progress and successful result output")
	noStartLog := flags.Bool("no-start-log", false, "do not print container startup logs")
	if err := flags.Parse(arguments); err != nil {
		return updateArguments{}, err
	}
	if flags.NArg() != 0 {
		return updateArguments{}, errors.New("update does not accept positional arguments")
	}
	if *service != serviceBackend {
		return updateArguments{}, errors.New("--service currently accepts only backend")
	}
	inputCount := 0
	for _, value := range []string{*file, *nativeJAR, *containerImage} {
		if value != "" {
			inputCount++
		}
	}
	if inputCount != 1 {
		return updateArguments{}, errors.New("exactly one of -f, --native-jar, and --container-image is required; update inputs are mutually exclusive")
	}
	if *containerImage != "" {
		return updateArguments{service: *service, inputType: daemonapi.InputTypeContainerImage, imageReference: *containerImage, quite: *quite, startLog: !*noStartLog}, nil
	}
	if *noStartLog {
		return updateArguments{}, errors.New("--no-start-log requires --container-image")
	}
	inputType := daemonapi.InputTypeRepackZIP
	inputFile := *file
	if *nativeJAR != "" {
		inputType = daemonapi.InputTypeNativeJAR
		inputFile = *nativeJAR
	}
	absoluteFile, err := filepath.Abs(inputFile)
	if err != nil {
		return updateArguments{}, fmt.Errorf("resolve update package path: %w", err)
	}
	info, err := os.Lstat(absoluteFile)
	if err != nil {
		return updateArguments{}, fmt.Errorf("inspect update package %s: %w", absoluteFile, err)
	}
	if !info.Mode().IsRegular() || info.Mode()&os.ModeSymlink != 0 {
		return updateArguments{}, fmt.Errorf("update package is not a direct regular file: %s", absoluteFile)
	}
	return updateArguments{service: *service, inputType: inputType, file: absoluteFile, quite: *quite}, nil
}

// parseRestartArgs 解析 restart 子命令的 flag 参数并做业务校验。
// 它要求 --service 必须为 backend，且不接受任何位置参数；校验失败时向 output 写入原因并返回 error。
func parseRestartArgs(arguments []string, output io.Writer) (restartArguments, error) {
	flags := flag.NewFlagSet("restart", flag.ContinueOnError)
	flags.SetOutput(output)
	service := flags.String("service", "", "service to restart")
	quite := flags.Bool("quite", false, "suppress progress and successful result output")
	if err := flags.Parse(arguments); err != nil {
		return restartArguments{}, err
	}
	if flags.NArg() != 0 {
		return restartArguments{}, errors.New("restart does not accept positional arguments")
	}
	if *service != serviceBackend {
		return restartArguments{}, errors.New("--service currently accepts only backend")
	}
	return restartArguments{service: *service, quite: *quite}, nil
}

// runServe 以守护进程服务端角色运行：初始化日志、获取进程锁、加载部署配置、
// 打开事务存储与协调器、构建 Nginx 控制器与后端更新器，最后通过 daemonserver 开始服务。
// 它使用具名返回 result 以便在各资源清理阶段合并所有 Close 错误，最终返回服务端的运行错误。
func runServe(ctx context.Context) (result error) {
	logger, logCloser, err := logging.New(runtimepaths.Log)
	if err != nil {
		return err
	}
	defer func() { result = errors.Join(result, logCloser.Close()) }()

	lock, err := processlock.Acquire(runtimepaths.Lock)
	if err != nil {
		return err
	}
	defer func() { result = errors.Join(result, lock.Close()) }()

	config, err := deploymentconfig.Load(deploymentconfig.DefaultPath)
	if err != nil {
		return err
	}
	store, err := transaction.OpenStore(ctx, runtimepaths.Database)
	if err != nil {
		return err
	}
	defer func() { result = errors.Join(result, store.Close()) }()
	coordinator, err := transaction.NewCoordinator(store, logger)
	if err != nil {
		return err
	}
	gateway, err := hostnginx.NewController(
		runtimepaths.HostNginxConfig,
		runtimepaths.HostNginxExecutable,
	)
	if err != nil {
		return err
	}
	httpClient := &http.Client{Timeout: 5 * time.Second}
	var updater *backendupdate.Updater
	switch config.Backend.Type {
	case deploymentconfig.BackendTypeNative:
		releaseStore, err := filestore.New(config.Backend.ReleaseDir)
		if err != nil {
			return err
		}
		units, err := systemd.NewSystemctl(config.Backend.SystemctlPath)
		if err != nil {
			return err
		}
		updater, err = backendupdate.New(config, runtimepaths.WorkRoot, store, coordinator, releaseStore, units, gateway, httpClient, logger)
	case deploymentconfig.BackendTypeContainer:
		var engine *containerengine.MobyEngine
		engine, err = containerengine.NewMobyEngine()
		if err == nil {
			defer func() { result = errors.Join(result, engine.Close()) }()
			updater, err = backendupdate.NewContainer(config, runtimepaths.WorkRoot, store, coordinator, engine, gateway, httpClient, logger)
		}
	default:
		err = fmt.Errorf("unsupported backend.type %q", config.Backend.Type)
	}
	if err != nil {
		return err
	}
	server, err := daemonserver.New(runtimepaths.Socket, updater, logger)
	if err != nil {
		return err
	}
	return server.Serve(ctx)
}

// writeUsage 向 output 写出命令行客户端各子命令的用法说明。
func writeUsage(output io.Writer) {
	fmt.Fprintln(output, "usage:")
	fmt.Fprintln(output, "  ymsctl update --service backend -f <repack.zip> [--quite]")
	fmt.Fprintln(output, "  ymsctl update --service backend --native-jar <backend.jar> [--quite]")
	fmt.Fprintln(output, "  ymsctl update --service backend --container-image <image-ref> [--no-start-log] [--quite]")
	fmt.Fprintln(output, "  ymsctl restart --service backend [--quite]")
	fmt.Fprintln(output, "  ymsctl list [--limit <n>] [--service backend] [--state <state>] [--json]")
}

// writeUpdateProgress 把一条进度事件格式化写入 output：状态字段左对齐占 14 列，
// 状态为空时显示为 INFO，随后输出事件消息。
func writeUpdateProgress(output io.Writer, event daemonapi.Response) {
	state := event.State
	if state == "" {
		state = "INFO"
	}
	fmt.Fprintf(output, "%-14s %s\n", state, event.Message)
}

// runList 执行 list 子命令：解析过滤参数，打开事务存储读取最近事务，
// 按是否指定 --json 决定以稳定 JSON 或制表符分隔的表格形式输出到 stdout。
// 它支持 --limit、--service、--state、--json 四个选项，返回查询或输出阶段的错误。
func runList(ctx context.Context, arguments []string, stdout, stderr io.Writer) error {
	flags := flag.NewFlagSet("list", flag.ContinueOnError)
	flags.SetOutput(stderr)
	limit := flags.Int("limit", 20, "maximum number of operations to show")
	service := flags.String("service", "", "exact service filter")
	state := flags.String("state", "", "exact transaction state filter")
	jsonOutput := flags.Bool("json", false, "write stable JSON")
	if err := flags.Parse(arguments); err != nil {
		return err
	}
	if flags.NArg() != 0 {
		return errors.New("list does not accept positional arguments")
	}
	if *service != "" && *service != serviceBackend {
		return errors.New("--service currently accepts only backend")
	}
	store, err := transaction.OpenStore(ctx, runtimepaths.Database)
	if err != nil {
		return err
	}
	defer store.Close()
	items, err := store.ListRecent(ctx, transaction.ListFilter{Limit: *limit, Service: *service, State: transaction.State(*state)})
	if err != nil {
		return err
	}
	if *jsonOutput {
		return json.NewEncoder(stdout).Encode(items)
	}
	fmt.Fprintln(stdout, "TIME\tTRANSACTION\tSERVICE\tSTATE\tSOURCE")
	for _, item := range items {
		fmt.Fprintf(stdout, "%s\t%s\t%s\t%s\t%s\n", item.CreatedAt.Local().Format("2006-01-02 15:04:05"), item.ID, item.Service, item.State, item.Source)
	}
	return nil
}