package storage

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"sync"
	"time"

	"github.com/frisbee-tournament/backend/internal/models"
)

type Store struct {
	dataDir string
	mu      sync.RWMutex
}

func New(dataDir string) *Store {
	return &Store{dataDir: dataDir}
}

func (s *Store) ensureDir(path string) error {
	return os.MkdirAll(path, 0755)
}

func (s *Store) readJSON(path string, v any) error {
	data, err := os.ReadFile(path)
	if err != nil {
		return err
	}
	return json.Unmarshal(data, v)
}

func (s *Store) writeJSON(path string, v any) error {
	data, err := json.MarshalIndent(v, "", "  ")
	if err != nil {
		return err
	}
	if err := s.ensureDir(filepath.Dir(path)); err != nil {
		return err
	}
	return os.WriteFile(path, data, 0644)
}

// --- Tournaments ---

func (s *Store) tournamentsFile() string {
	return filepath.Join(s.dataDir, "tournaments.json")
}

func (s *Store) GetTournaments() ([]models.Tournament, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	var ts []models.Tournament
	if err := s.readJSON(s.tournamentsFile(), &ts); err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	return ts, nil
}

func (s *Store) GetTournament(id string) (*models.Tournament, error) {
	ts, err := s.GetTournaments()
	if err != nil {
		return nil, err
	}
	for _, t := range ts {
		if t.ID == id {
			return &t, nil
		}
	}
	return nil, fmt.Errorf("tournament %s not found", id)
}

func (s *Store) SaveTournaments(ts []models.Tournament) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.writeJSON(s.tournamentsFile(), ts)
}

// --- Schedule ---

func (s *Store) tourneyDir(tourneyID string) string {
	return filepath.Join(s.dataDir, "tournaments", tourneyID)
}

func (s *Store) GetSchedule(tourneyID string) (*models.Schedule, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	var sched models.Schedule
	path := filepath.Join(s.tourneyDir(tourneyID), "schedule.json")
	if err := s.readJSON(path, &sched); err != nil {
		if os.IsNotExist(err) {
			return &models.Schedule{TourneyID: tourneyID}, nil
		}
		return nil, err
	}
	return &sched, nil
}

func (s *Store) SaveSchedule(sched *models.Schedule) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	path := filepath.Join(s.tourneyDir(sched.TourneyID), "schedule.json")
	return s.writeJSON(path, sched)
}

// --- Score ---

func (s *Store) gameDir(tourneyID string) string {
	return filepath.Join(s.tourneyDir(tourneyID), "games")
}

func (s *Store) GetScore(tourneyID, gameID string) (*models.ScoreState, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	var state models.ScoreState
	path := filepath.Join(s.gameDir(tourneyID), gameID+"_score.json")
	if err := s.readJSON(path, &state); err != nil {
		if os.IsNotExist(err) {
			return &models.ScoreState{GameID: gameID}, nil
		}
		return nil, err
	}
	return &state, nil
}

func (s *Store) SaveScore(tourneyID string, state *models.ScoreState) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	path := filepath.Join(s.gameDir(tourneyID), state.GameID+"_score.json")
	return s.writeJSON(path, state)
}

func (s *Store) AppendAuditLog(tourneyID, gameID string, entry models.AuditEntry) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	dir := s.gameDir(tourneyID)
	if err := s.ensureDir(dir); err != nil {
		return err
	}
	path := filepath.Join(dir, gameID+"_audit.jsonl")
	f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	defer f.Close()
	data, err := json.Marshal(entry)
	if err != nil {
		return err
	}
	_, err = f.Write(append(data, '\n'))
	return err
}

func (s *Store) GetAuditLog(tourneyID, gameID string) ([]models.AuditEntry, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	path := filepath.Join(s.gameDir(tourneyID), gameID+"_audit.jsonl")
	data, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	var entries []models.AuditEntry
	for _, line := range splitLines(data) {
		if len(line) == 0 {
			continue
		}
		var e models.AuditEntry
		if err := json.Unmarshal(line, &e); err != nil {
			continue
		}
		entries = append(entries, e)
	}
	return entries, nil
}

// --- Questionnaire ---

func (s *Store) GetQuestionnaireConfig(tourneyID string) (*models.QuestionnaireConfig, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	var cfg models.QuestionnaireConfig
	path := filepath.Join(s.tourneyDir(tourneyID), "questionnaire_config.json")
	if err := s.readJSON(path, &cfg); err != nil {
		if os.IsNotExist(err) {
			return &models.QuestionnaireConfig{TourneyID: tourneyID}, nil
		}
		return nil, err
	}
	return &cfg, nil
}

func (s *Store) SaveQuestionnaireResponse(tourneyID string, resp *models.QuestionnaireResponse) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	resp.SubmittedAt = time.Now()
	if resp.ID == "" {
		resp.ID = fmt.Sprintf("resp_%d", time.Now().UnixNano())
	}
	dir := filepath.Join(s.tourneyDir(tourneyID), "questionnaire_responses")
	path := filepath.Join(dir, resp.ID+".json")
	return s.writeJSON(path, resp)
}

func (s *Store) GetQuestionnaireResponses(tourneyID string) ([]models.QuestionnaireResponse, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	dir := filepath.Join(s.tourneyDir(tourneyID), "questionnaire_responses")
	entries, err := os.ReadDir(dir)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, err
	}
	var resps []models.QuestionnaireResponse
	for _, e := range entries {
		if filepath.Ext(e.Name()) != ".json" {
			continue
		}
		var r models.QuestionnaireResponse
		if err := s.readJSON(filepath.Join(dir, e.Name()), &r); err == nil {
			resps = append(resps, r)
		}
	}
	return resps, nil
}

// --- Results ---

func (s *Store) GetResults(tourneyID string) (*models.FinalResults, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	var res models.FinalResults
	path := filepath.Join(s.tourneyDir(tourneyID), "results.json")
	if err := s.readJSON(path, &res); err != nil {
		if os.IsNotExist(err) {
			return &models.FinalResults{TourneyID: tourneyID}, nil
		}
		return nil, err
	}
	return &res, nil
}

func splitLines(data []byte) [][]byte {
	var lines [][]byte
	start := 0
	for i, b := range data {
		if b == '\n' {
			lines = append(lines, data[start:i])
			start = i + 1
		}
	}
	if start < len(data) {
		lines = append(lines, data[start:])
	}
	return lines
}