package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/urfave/cli/v2"

	"git.t-juice.club/torjus/labmcp/internal/gitexplorer"
	"git.t-juice.club/torjus/labmcp/internal/mcp"
)

const version = "0.1.0"

func main() {
	app := &cli.App{
		Name:    "git-explorer",
		Usage:   "Read-only MCP server for git repository exploration",
		Version: version,
		Flags: []cli.Flag{
			&cli.StringFlag{
				Name:    "repo",
				Aliases: []string{"r"},
				Usage:   "Path to git repository",
				EnvVars: []string{"GIT_REPO_PATH"},
				Value:   ".",
			},
			&cli.StringFlag{
				Name:    "default-remote",
				Usage:   "Default remote name",
				EnvVars: []string{"GIT_DEFAULT_REMOTE"},
				Value:   "origin",
			},
		},
		Commands: []*cli.Command{
			serveCommand(),
			resolveCommand(),
			logCommand(),
			showCommand(),
			diffCommand(),
			catCommand(),
			branchesCommand(),
			searchCommand(),
		},
	}

	if err := app.Run(os.Args); err != nil {
		log.Fatal(err)
	}
}

func serveCommand() *cli.Command {
	return &cli.Command{
		Name:  "serve",
		Usage: "Run MCP server for git exploration",
		Flags: []cli.Flag{
			&cli.StringFlag{
				Name:    "transport",
				Aliases: []string{"t"},
				Usage:   "Transport type: 'stdio' or 'http'",
				Value:   "stdio",
			},
			&cli.StringFlag{
				Name:  "http-address",
				Usage: "HTTP listen address",
				Value: "127.0.0.1:8085",
			},
			&cli.StringFlag{
				Name:  "http-endpoint",
				Usage: "HTTP endpoint path",
				Value: "/mcp",
			},
			&cli.StringSliceFlag{
				Name:  "allowed-origins",
				Usage: "Allowed Origin headers for CORS",
			},
			&cli.StringFlag{
				Name:  "tls-cert",
				Usage: "TLS certificate file",
			},
			&cli.StringFlag{
				Name:  "tls-key",
				Usage: "TLS key file",
			},
			&cli.DurationFlag{
				Name:  "session-ttl",
				Usage: "Session TTL for HTTP transport",
				Value: 30 * time.Minute,
			},
		},
		Action: func(c *cli.Context) error {
			return runServe(c)
		},
	}
}

func resolveCommand() *cli.Command {
	return &cli.Command{
		Name:      "resolve",
		Usage:     "Resolve a ref to a commit hash",
		ArgsUsage: "<ref>",
		Action: func(c *cli.Context) error {
			if c.NArg() < 1 {
				return fmt.Errorf("ref argument required")
			}
			return runResolve(c, c.Args().First())
		},
	}
}

func logCommand() *cli.Command {
	return &cli.Command{
		Name:  "log",
		Usage: "Show commit log",
		Flags: []cli.Flag{
			&cli.StringFlag{
				Name:  "ref",
				Usage: "Starting ref (default: HEAD)",
				Value: "HEAD",
			},
			&cli.IntFlag{
				Name:    "limit",
				Aliases: []string{"n"},
				Usage:   "Maximum number of commits",
				Value:   10,
			},
			&cli.StringFlag{
				Name:  "author",
				Usage: "Filter by author",
			},
			&cli.StringFlag{
				Name:  "path",
				Usage: "Filter by path",
			},
		},
		Action: func(c *cli.Context) error {
			return runLog(c)
		},
	}
}

func showCommand() *cli.Command {
	return &cli.Command{
		Name:      "show",
		Usage:     "Show commit details",
		ArgsUsage: "<ref>",
		Flags: []cli.Flag{
			&cli.BoolFlag{
				Name:  "stats",
				Usage: "Include file statistics",
				Value: true,
			},
		},
		Action: func(c *cli.Context) error {
			ref := "HEAD"
			if c.NArg() > 0 {
				ref = c.Args().First()
			}
			return runShow(c, ref)
		},
	}
}

func diffCommand() *cli.Command {
	return &cli.Command{
		Name:      "diff",
		Usage:     "Show files changed between two commits",
		ArgsUsage: "<from-ref> <to-ref>",
		Action: func(c *cli.Context) error {
			if c.NArg() < 2 {
				return fmt.Errorf("both from-ref and to-ref arguments required")
			}
			return runDiff(c, c.Args().Get(0), c.Args().Get(1))
		},
	}
}

func catCommand() *cli.Command {
	return &cli.Command{
		Name:      "cat",
		Usage:     "Show file contents at a commit",
		ArgsUsage: "<ref> <path>",
		Action: func(c *cli.Context) error {
			if c.NArg() < 2 {
				return fmt.Errorf("both ref and path arguments required")
			}
			return runCat(c, c.Args().Get(0), c.Args().Get(1))
		},
	}
}

func branchesCommand() *cli.Command {
	return &cli.Command{
		Name:  "branches",
		Usage: "List branches",
		Flags: []cli.Flag{
			&cli.BoolFlag{
				Name:    "remote",
				Aliases: []string{"r"},
				Usage:   "Include remote branches",
			},
		},
		Action: func(c *cli.Context) error {
			return runBranches(c)
		},
	}
}

func searchCommand() *cli.Command {
	return &cli.Command{
		Name:      "search",
		Usage:     "Search commit messages",
		ArgsUsage: "<query>",
		Flags: []cli.Flag{
			&cli.StringFlag{
				Name:  "ref",
				Usage: "Starting ref (default: HEAD)",
				Value: "HEAD",
			},
			&cli.IntFlag{
				Name:    "limit",
				Aliases: []string{"n"},
				Usage:   "Maximum number of results",
				Value:   20,
			},
		},
		Action: func(c *cli.Context) error {
			if c.NArg() < 1 {
				return fmt.Errorf("query argument required")
			}
			return runSearch(c, c.Args().First())
		},
	}
}

func runServe(c *cli.Context) error {
	ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer cancel()

	repoPath := c.String("repo")
	client, err := gitexplorer.NewGitClient(repoPath, c.String("default-remote"))
	if err != nil {
		return fmt.Errorf("failed to open repository: %w", err)
	}

	logger := log.New(os.Stderr, "[mcp] ", log.LstdFlags)
	config := mcp.DefaultGitExplorerConfig()

	server := mcp.NewGenericServer(logger, config)
	gitexplorer.RegisterHandlers(server, client)

	transport := c.String("transport")
	switch transport {
	case "stdio":
		logger.Printf("Starting git-explorer MCP server on stdio (repo: %s)...", repoPath)
		return server.Run(ctx, os.Stdin, os.Stdout)

	case "http":
		httpConfig := mcp.HTTPConfig{
			Address:        c.String("http-address"),
			Endpoint:       c.String("http-endpoint"),
			AllowedOrigins: c.StringSlice("allowed-origins"),
			SessionTTL:     c.Duration("session-ttl"),
			TLSCertFile:    c.String("tls-cert"),
			TLSKeyFile:     c.String("tls-key"),
		}
		httpTransport := mcp.NewHTTPTransport(server, httpConfig)
		return httpTransport.Run(ctx)

	default:
		return fmt.Errorf("unknown transport: %s (use 'stdio' or 'http')", transport)
	}
}

func getClient(c *cli.Context) (*gitexplorer.GitClient, error) {
	return gitexplorer.NewGitClient(c.String("repo"), c.String("default-remote"))
}

func runResolve(c *cli.Context, ref string) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	result, err := client.ResolveRef(ref)
	if err != nil {
		return err
	}

	fmt.Printf("%s (%s) -> %s\n", result.Ref, result.Type, result.Commit)
	return nil
}

func runLog(c *cli.Context) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	entries, err := client.GetLog(
		c.String("ref"),
		c.Int("limit"),
		c.String("author"),
		"",
		c.String("path"),
	)
	if err != nil {
		return err
	}

	if len(entries) == 0 {
		fmt.Println("No commits found.")
		return nil
	}

	for _, e := range entries {
		fmt.Printf("%s %s\n", e.ShortHash, e.Subject)
		fmt.Printf("  Author: %s <%s>\n", e.Author, e.Email)
		fmt.Printf("  Date:   %s\n\n", e.Date.Format("2006-01-02 15:04:05"))
	}

	return nil
}

func runShow(c *cli.Context, ref string) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	info, err := client.GetCommitInfo(ref, c.Bool("stats"))
	if err != nil {
		return err
	}

	fmt.Printf("commit %s\n", info.Hash)
	fmt.Printf("Author: %s <%s>\n", info.Author, info.Email)
	fmt.Printf("Date:   %s\n", info.Date.Format("2006-01-02 15:04:05"))

	if len(info.Parents) > 0 {
		fmt.Printf("Parents: %v\n", info.Parents)
	}

	if info.Stats != nil {
		fmt.Printf("\n%d file(s) changed, %d insertions(+), %d deletions(-)\n",
			info.Stats.FilesChanged, info.Stats.Additions, info.Stats.Deletions)
	}

	fmt.Printf("\n%s", info.Message)

	return nil
}

func runDiff(c *cli.Context, fromRef, toRef string) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	result, err := client.GetDiffFiles(fromRef, toRef)
	if err != nil {
		return err
	}

	if len(result.Files) == 0 {
		fmt.Println("No files changed.")
		return nil
	}

	fmt.Printf("Comparing %s..%s\n\n", result.FromCommit[:7], result.ToCommit[:7])

	for _, f := range result.Files {
		status := f.Status[0:1] // First letter: A, M, D, R
		path := f.Path
		if f.OldPath != "" {
			path = fmt.Sprintf("%s -> %s", f.OldPath, f.Path)
		}
		fmt.Printf("%s  %s  (+%d -%d)\n", status, path, f.Additions, f.Deletions)
	}

	return nil
}

func runCat(c *cli.Context, ref, path string) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	content, err := client.GetFileAtCommit(ref, path)
	if err != nil {
		return err
	}

	fmt.Print(content.Content)
	return nil
}

func runBranches(c *cli.Context) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	result, err := client.ListBranches(c.Bool("remote"))
	if err != nil {
		return err
	}

	if result.Total == 0 {
		fmt.Println("No branches found.")
		return nil
	}

	for _, b := range result.Branches {
		marker := " "
		if b.IsHead {
			marker = "*"
		}
		remoteMarker := ""
		if b.IsRemote {
			remoteMarker = " (remote)"
		}
		fmt.Printf("%s %s -> %s%s\n", marker, b.Name, b.Commit[:7], remoteMarker)
	}

	return nil
}

func runSearch(c *cli.Context, query string) error {
	client, err := getClient(c)
	if err != nil {
		return err
	}

	result, err := client.SearchCommits(c.String("ref"), query, c.Int("limit"))
	if err != nil {
		return err
	}

	if result.Count == 0 {
		fmt.Printf("No commits matching '%s'.\n", query)
		return nil
	}

	fmt.Printf("Found %d commit(s) matching '%s':\n\n", result.Count, query)
	for _, e := range result.Commits {
		fmt.Printf("%s %s\n", e.ShortHash, e.Subject)
		fmt.Printf("  Author: %s <%s>\n", e.Author, e.Email)
		fmt.Printf("  Date:   %s\n\n", e.Date.Format("2006-01-02 15:04:05"))
	}

	return nil
}