package servercmd

import (
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
)

type Config struct {
	WorkspacesDir string
	ProjectRoot   string
	Port          int
	Addr          string
}

type RunnerDeps struct {
	StdErr         io.Writer
	InitRuntime    func(Config) (io.Closer, error)
	BuildMux       func(Config) http.Handler
	ListenAndServe func(string, http.Handler) error
}

func Run(args []string, deps RunnerDeps) error {
	cfg, err := parseConfig(args)
	if err != nil {
		return err
	}
	if deps.BuildMux == nil {
		return fmt.Errorf("server mux builder is not configured")
	}

	listenAndServe := deps.ListenAndServe
	if listenAndServe == nil {
		listenAndServe = http.ListenAndServe
	}

	stderr := deps.StdErr
	if stderr == nil {
		stderr = os.Stderr
	}

	return runWithConfig(cfg, deps, stderr, listenAndServe)
}

func parseConfig(args []string) (Config, error) {
	flagSet := flag.NewFlagSet("server", flag.ExitOnError)
	port := flagSet.Int("port", 3000, "HTTP server port")
	wsDir := flagSet.String("workspaces-dir", "", "directory containing workspace worktrees (required)")
	flagSet.Parse(args)

	if *wsDir == "" {
		return Config{}, fmt.Errorf("--workspaces-dir is required")
	}

	absDir, err := filepath.Abs(*wsDir)
	if err != nil {
		return Config{}, fmt.Errorf("resolving workspaces-dir: %w", err)
	}
	info, err := os.Stat(absDir)
	if err != nil || !info.IsDir() {
		return Config{}, fmt.Errorf("workspaces-dir does not exist or is not a directory: %s", absDir)
	}
	return Config{
		WorkspacesDir: absDir,
		ProjectRoot:   filepath.Dir(absDir),
		Port:          *port,
		Addr:          fmt.Sprintf(":%d", *port),
	}, nil
}

func runWithConfig(cfg Config, deps RunnerDeps, stderr io.Writer, listenAndServe func(string, http.Handler) error) error {
	var closer io.Closer
	var err error
	if deps.InitRuntime != nil {
		closer, err = deps.InitRuntime(cfg)
		if err != nil {
			return fmt.Errorf("opening central database: %w", err)
		}
		if closer != nil {
			defer closer.Close()
		}
	}

	handler := deps.BuildMux(cfg)
	fmt.Fprintf(stderr, "inbox API server listening on http://localhost%s\n", cfg.Addr)
	fmt.Fprintf(stderr, "workspaces dir: %s\n", cfg.WorkspacesDir)
	return listenAndServe(cfg.Addr, handler)
}