// This file is part of the happyDeliver (R) project.
// Copyright (c) 2025 happyDomain
// Authors: Pierre-Olivier Mercier, et al.
//
// This program is offered under a commercial and under the AGPL license.
// For commercial licensing, contact us at <contact@happydomain.org>.
//
// For AGPL licensing:
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package storage

import (
	"errors"
	"fmt"
	"time"

	"github.com/google/uuid"
	"gorm.io/driver/postgres"
	"gorm.io/driver/sqlite"
	"gorm.io/gorm"
)

var (
	ErrNotFound      = errors.New("not found")
	ErrAlreadyExists = errors.New("already exists")
)

// Storage interface defines operations for persisting and retrieving data
type Storage interface {
	// Report operations
	CreateReport(testID uuid.UUID, rawEmail []byte, reportJSON []byte) (*Report, error)
	GetReport(testID uuid.UUID) (reportJSON []byte, rawEmail []byte, err error)
	ReportExists(testID uuid.UUID) (bool, error)
	UpdateReport(testID uuid.UUID, reportJSON []byte) error
	DeleteOldReports(olderThan time.Time) (int64, error)

	// Close closes the database connection
	Close() error
}

// DBStorage implements Storage using GORM
type DBStorage struct {
	db *gorm.DB
}

// NewStorage creates a new storage instance based on database type
func NewStorage(dbType, dsn string) (Storage, error) {
	var dialector gorm.Dialector

	switch dbType {
	case "sqlite":
		dialector = sqlite.Open(dsn)
	case "postgres":
		dialector = postgres.Open(dsn)
	default:
		return nil, fmt.Errorf("unsupported database type: %s", dbType)
	}

	db, err := gorm.Open(dialector, &gorm.Config{})
	if err != nil {
		return nil, fmt.Errorf("failed to connect to database: %w", err)
	}

	// Auto-migrate the schema
	if err := db.AutoMigrate(&Report{}); err != nil {
		return nil, fmt.Errorf("failed to migrate database schema: %w", err)
	}

	return &DBStorage{db: db}, nil
}

// CreateReport creates a new report for a test
func (s *DBStorage) CreateReport(testID uuid.UUID, rawEmail []byte, reportJSON []byte) (*Report, error) {
	dbReport := &Report{
		TestID:     testID,
		RawEmail:   rawEmail,
		ReportJSON: reportJSON,
	}

	if err := s.db.Create(dbReport).Error; err != nil {
		return nil, fmt.Errorf("failed to create report: %w", err)
	}

	return dbReport, nil
}

// ReportExists checks if a report exists for the given test ID
func (s *DBStorage) ReportExists(testID uuid.UUID) (bool, error) {
	var count int64
	if err := s.db.Model(&Report{}).Where("test_id = ?", testID).Count(&count).Error; err != nil {
		return false, fmt.Errorf("failed to check report existence: %w", err)
	}
	return count > 0, nil
}

// GetReport retrieves a report by test ID, returning the raw JSON and email bytes
func (s *DBStorage) GetReport(testID uuid.UUID) ([]byte, []byte, error) {
	var dbReport Report
	if err := s.db.Where("test_id = ?", testID).Order("created_at DESC").First(&dbReport).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, nil, ErrNotFound
		}
		return nil, nil, fmt.Errorf("failed to get report: %w", err)
	}

	return dbReport.ReportJSON, dbReport.RawEmail, nil
}

// UpdateReport updates the report JSON for an existing test ID
func (s *DBStorage) UpdateReport(testID uuid.UUID, reportJSON []byte) error {
	result := s.db.Model(&Report{}).Where("test_id = ?", testID).Update("report_json", reportJSON)
	if result.Error != nil {
		return fmt.Errorf("failed to update report: %w", result.Error)
	}
	if result.RowsAffected == 0 {
		return ErrNotFound
	}
	return nil
}

// DeleteOldReports deletes reports older than the specified time
func (s *DBStorage) DeleteOldReports(olderThan time.Time) (int64, error) {
	result := s.db.Where("created_at < ?", olderThan).Delete(&Report{})
	if result.Error != nil {
		return 0, fmt.Errorf("failed to delete old reports: %w", result.Error)
	}
	return result.RowsAffected, nil
}

// Close closes the database connection
func (s *DBStorage) Close() error {
	sqlDB, err := s.db.DB()
	if err != nil {
		return err
	}
	return sqlDB.Close()
}

// GetAllReports retrieves all reports from the database
func GetAllReports(s Storage) ([]Report, error) {
	dbStorage, ok := s.(*DBStorage)
	if !ok {
		return nil, fmt.Errorf("storage type does not support GetAllReports")
	}

	var reports []Report
	if err := dbStorage.db.Find(&reports).Error; err != nil {
		return nil, fmt.Errorf("failed to retrieve reports: %w", err)
	}

	return reports, nil
}

// CreateReportFromBackup creates a report from backup data, preserving timestamps
func CreateReportFromBackup(s Storage, report *Report) (*Report, error) {
	dbStorage, ok := s.(*DBStorage)
	if !ok {
		return nil, fmt.Errorf("storage type does not support CreateReportFromBackup")
	}

	// Use Create to insert the report with all fields including timestamps
	if err := dbStorage.db.Create(report).Error; err != nil {
		return nil, fmt.Errorf("failed to create report from backup: %w", err)
	}

	return report, nil
}