package session

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"
)

// Session is the on-disk capture result (shared with restream tooling).
type Session struct {
	App        string `json:"app"`
	Channel    string `json:"channel,omitempty"`
	CapturedAt string `json:"captured_at"`
	PSSH       string `json:"pssh,omitempty"`
	Auth       string `json:"auth,omitempty"`
	PID        string `json:"pid,omitempty"`
	Key        string `json:"key,omitempty"`
	KID        string `json:"kid,omitempty"`
	KeyHex     string `json:"key_hex,omitempty"`
	MPD        string `json:"mpd,omitempty"`
	LicenseURL string `json:"license_url,omitempty"`
}

// Write creates outputs/<app>/<stamp>/session.json (+ field txt files + latest).
func Write(root, app string, s Session) (string, error) {
	stamp := time.Now().Format("20060102-150405")
	dir := filepath.Join(root, "outputs", app, stamp)
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return "", err
	}
	s.App = app
	if s.CapturedAt == "" {
		s.CapturedAt = time.Now().Format(time.RFC3339)
	}
	if s.Key != "" && s.KID == "" {
		parts := strings.SplitN(s.Key, ":", 2)
		if len(parts) == 2 {
			s.KID = parts[0]
			s.KeyHex = parts[1]
		}
	}
	raw, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return "", err
	}
	path := filepath.Join(dir, "session.json")
	if err := os.WriteFile(path, append(raw, '\n'), 0o644); err != nil {
		return "", err
	}
	fields := map[string]string{
		"pssh": s.PSSH,
		"auth": s.Auth,
		"pid":  s.PID,
		"key":  s.Key,
		"mpd":  s.MPD,
	}
	for name, val := range fields {
		if val == "" {
			continue
		}
		_ = os.WriteFile(filepath.Join(dir, name+".txt"), []byte(val+"\n"), 0o644)
	}
	latest := filepath.Join(root, "outputs", app, "latest")
	_ = os.RemoveAll(latest)
	// Best-effort directory copy for Windows (symlinks often need admin).
	if err := copyDir(dir, latest); err != nil {
		fmt.Fprintf(os.Stderr, "[!] latest link/copy: %v\n", err)
	}
	return path, nil
}

func copyDir(src, dst string) error {
	if err := os.MkdirAll(dst, 0o755); err != nil {
		return err
	}
	entries, err := os.ReadDir(src)
	if err != nil {
		return err
	}
	for _, e := range entries {
		in := filepath.Join(src, e.Name())
		out := filepath.Join(dst, e.Name())
		if e.IsDir() {
			if err := copyDir(in, out); err != nil {
				return err
			}
			continue
		}
		b, err := os.ReadFile(in)
		if err != nil {
			return err
		}
		if err := os.WriteFile(out, b, 0o644); err != nil {
			return err
		}
	}
	return nil
}