// Command wikijs-mcp exposes a WikiJS instance as a Model Context Protocol
// server over stdio or streamable HTTP.
package main

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"

	"wikijs-mcp/internal/config"
	"wikijs-mcp/internal/server"
	"wikijs-mcp/internal/transport"
	"wikijs-mcp/internal/wikijs"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

// version is set at build time with -ldflags "-X main.version=...".
var version = "dev"

func main() {
	if err := run(os.Args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "wikijs-mcp: %v\n", err)
		os.Exit(1)
	}
}

func run(args []string) error {
	envFile, useEnvFile, err := envFileFromArgs(args)
	if err != nil {
		return err
	}
	if useEnvFile {
		if err := config.LoadEnvFile(envFile); err != nil {
			return err
		}
	} else if err := config.LoadDotEnv(); err != nil {
		return err
	}

	cfg, err := config.Load()
	if err != nil {
		return err
	}

	fs := flag.NewFlagSet("wikijs-mcp", flag.ContinueOnError)
	fs.SetOutput(os.Stderr)
	fs.Usage = func() {
		out := fs.Output()
		fmt.Fprintln(out, "Usage: wikijs-mcp [flags]")
		fmt.Fprintln(out)
		fmt.Fprintln(out, "WikiJS connection (environment):")
		fmt.Fprintln(out, "  WIKIJS_URL          Base URL of the WikiJS instance (required)")
		fmt.Fprintln(out, "  WIKIJS_API_KEY      WikiJS API key (required)")
		fmt.Fprintln(out, "  WIKIJS_ENABLE_EDIT  Expose create_page and edit_page (default false)")
		fmt.Fprintln(out, "  WIKIJS_TIMEOUT      GraphQL request timeout (default 30s)")
		fmt.Fprintln(out)
		fmt.Fprintln(out, "Other environment:")
		fmt.Fprintln(out, "  ENV_FILE            env file to load (default \".env\")")
		fmt.Fprintln(out, "  MCP_AUTH_TOKEN      bearer token for HTTP (required for non-loopback)")
		fmt.Fprintln(out)
		fmt.Fprintln(out, "Flags:")
		fs.PrintDefaults()
	}
	fs.String("env-file", "", "env file to load (overrides ENV_FILE and .env)")
	fs.StringVar(&cfg.Transport, "transport", cfg.Transport, `"stdio" or "http"`)
	fs.StringVar(&cfg.Addr, "addr", cfg.Addr, "listen address for the HTTP transport")
	fs.StringVar(&cfg.Path, "path", cfg.Path, "MCP endpoint path for the HTTP transport")
	fs.BoolVar(&cfg.Stateless, "stateless", cfg.Stateless, "disable MCP sessions on the HTTP transport")
	logLevel := strings.ToLower(cfg.LogLevel.String())
	fs.StringVar(&logLevel, "log-level", logLevel, "debug, info, warn, or error")
	showVersion := fs.Bool("version", false, "print the version and exit")

	if err := fs.Parse(args); err != nil {
		if errors.Is(err, flag.ErrHelp) {
			return nil
		}
		return err
	}
	if *showVersion {
		fmt.Println(version)
		return nil
	}
	if fs.NArg() > 0 {
		return fmt.Errorf("unexpected arguments: %v", fs.Args())
	}
	if cfg.LogLevel, err = config.ParseLogLevel(logLevel); err != nil {
		return err
	}
	if err := cfg.Validate(); err != nil {
		return err
	}

	logger := newLogger(cfg.LogLevel)
	protocolLogger := newLogger(slog.LevelWarn)
	if cfg.LogLevel == slog.LevelDebug {
		protocolLogger = logger
	}

	wikiClient, err := wikijs.New(cfg.WikiJSURL, cfg.WikiJSAPIKey,
		wikijs.WithHTTPClient(&http.Client{Timeout: cfg.Timeout}),
		wikijs.WithLogger(logger),
		wikijs.WithUserAgent("wikijs-mcp/"+version),
	)
	if err != nil {
		return err
	}

	mcpServer := server.New(wikiClient, server.Options{
		Version:    version,
		EnableEdit: cfg.EnableEdit,
		Logger:     protocolLogger,
	})

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	switch cfg.Transport {
	case config.TransportStdio:
		logger.Info("WikiJS MCP server running", "transport", "stdio", "version", version, "edit", cfg.EnableEdit)
		if err := mcpServer.Run(ctx, &mcp.StdioTransport{}); err != nil && !errors.Is(err, context.Canceled) {
			return fmt.Errorf("stdio server: %w", err)
		}
		return nil

	case config.TransportHTTP:
		return transport.ServeHTTP(ctx, transport.HTTPOptions{
			Addr:           cfg.Addr,
			Path:           cfg.Path,
			Stateless:      cfg.Stateless,
			AuthToken:      cfg.AuthToken,
			Logger:         logger,
			ProtocolLogger: protocolLogger,
			NewServer:      func(*http.Request) *mcp.Server { return mcpServer },
		})

	default:
		return fmt.Errorf("unsupported transport %q", cfg.Transport)
	}
}

func newLogger(level slog.Level) *slog.Logger {
	return slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{
		Level: level,
	}))
}

// envFileFromArgs finds --env-file before flag parsing, because the env file
// must be loaded before the configuration is read. The regular flag set also
// defines --env-file so it appears in help and is parsed consistently.
func envFileFromArgs(args []string) (path string, found bool, err error) {
	for i := 0; i < len(args); i++ {
		arg := args[i]
		if arg == "--" {
			break
		}
		switch {
		case arg == "--env-file" || arg == "-env-file":
			if i+1 >= len(args) {
				return "", true, fmt.Errorf("flag needs an argument: %s", arg)
			}
			path = args[i+1]
			found = true
			i++
		case strings.HasPrefix(arg, "--env-file="):
			path = strings.TrimPrefix(arg, "--env-file=")
			found = true
		case strings.HasPrefix(arg, "-env-file="):
			path = strings.TrimPrefix(arg, "-env-file=")
			found = true
		}
	}
	if found && strings.TrimSpace(path) == "" {
		return "", true, errors.New("--env-file must not be empty")
	}
	return path, found, nil
}