package session

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

type Data struct {
	Spotify SpotifyState `json:"spotify"`
}

type SpotifyState struct {
	ClientID     string `json:"client_id,omitempty"`
	AccessToken  string `json:"access_token,omitempty"`
	RefreshToken string `json:"refresh_token,omitempty"`
	TokenType    string `json:"token_type,omitempty"`
	Scope        string `json:"scope,omitempty"`
	ExpiresAt    string `json:"expires_at,omitempty"`
}

func Load(path string) (Data, error) {
	path, err := expandPath(path)
	if err != nil {
		return Data{}, err
	}
	b, err := os.ReadFile(path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return Data{}, nil
		}
		return Data{}, fmt.Errorf("read session file: %w", err)
	}
	var d Data
	if err := json.Unmarshal(b, &d); err != nil {
		return Data{}, fmt.Errorf("decode session file: %w", err)
	}
	return d, nil
}

func Save(path string, d Data) error {
	path, err := expandPath(path)
	if err != nil {
		return err
	}

	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0o700); err != nil {
		return fmt.Errorf("create session directory: %w", err)
	}

	b, err := json.MarshalIndent(d, "", "  ")
	if err != nil {
		return fmt.Errorf("encode session file: %w", err)
	}

	tmp := path + ".tmp"
	if err := os.WriteFile(tmp, b, 0o600); err != nil {
		return fmt.Errorf("write temp session file: %w", err)
	}
	if err := os.Rename(tmp, path); err != nil {
		return fmt.Errorf("replace session file: %w", err)
	}
	return nil
}

func (s SpotifyState) ExpiresAtTime() time.Time {
	t, err := time.Parse(time.RFC3339, strings.TrimSpace(s.ExpiresAt))
	if err != nil {
		return time.Time{}
	}
	return t
}

func expandPath(path string) (string, error) {
	path = strings.TrimSpace(path)
	if path == "" {
		return "", fmt.Errorf("session path cannot be empty")
	}
	if strings.HasPrefix(path, "~/") || path == "~" {
		home, err := os.UserHomeDir()
		if err != nil {
			return "", fmt.Errorf("resolve home directory: %w", err)
		}
		if path == "~" {
			path = home
		} else {
			path = filepath.Join(home, strings.TrimPrefix(path, "~/"))
		}
	}
	return filepath.Clean(path), nil
}