package storage

import (
	"context"
	"database/sql"
	"fmt"
	"log"
	"time"
)

// AuditLogEntry represents a single audit log entry
type AuditLogEntry struct {
	ID         int64     `json:"id"`
	TaskID     string    `json:"task_id"`
	UserID     *string   `json:"user_id,omitempty"`
	Token      *string   `json:"token,omitempty"`
	Action     string    `json:"action"`
	AccessedAt time.Time `json:"accessed_at"`
	IPAddress  *string   `json:"ip_address,omitempty"`
}

// LogTaskAccess records an access event in the audit log.
func (db *DB) LogTaskAccess(taskID string, userID, token, action, ipAddress *string) error {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `INSERT INTO task_access_log (task_id, user_id, token, action, ip_address) 
			VALUES (?, ?, ?, ?, ?)`
	} else {
		query = `INSERT INTO task_access_log (task_id, user_id, token, action, ip_address) 
			VALUES ($1, $2, $3, $4, $5)`
	}

	_, err := db.conn.ExecContext(context.Background(), query, taskID, userID, token, action, ipAddress)
	if err != nil {
		return fmt.Errorf("failed to log task access: %w", err)
	}
	return nil
}

// GetAuditLogForTask retrieves audit log entries for a specific task.
func (db *DB) GetAuditLogForTask(taskID string, limit int) ([]*AuditLogEntry, error) {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `SELECT id, task_id, user_id, token, action, accessed_at, ip_address 
			FROM task_access_log 
			WHERE task_id = ? 
			ORDER BY accessed_at DESC 
			LIMIT ?`
	} else {
		query = `SELECT id, task_id, user_id, token, action, accessed_at, ip_address 
			FROM task_access_log 
			WHERE task_id = $1 
			ORDER BY accessed_at DESC 
			LIMIT $2`
	}

	rows, err := db.conn.QueryContext(context.Background(), query, taskID, limit)
	if err != nil {
		return nil, fmt.Errorf("failed to get audit log: %w", err)
	}
	defer func() {
		if err := rows.Close(); err != nil {
			log.Printf("ERROR: failed to close rows: %v", err)
		}
	}()

	return db.scanAuditLogEntries(rows)
}

// GetAuditLogForUser retrieves audit log entries for a specific user.
func (db *DB) GetAuditLogForUser(userID string, limit int) ([]*AuditLogEntry, error) {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `SELECT id, task_id, user_id, token, action, accessed_at, ip_address 
			FROM task_access_log 
			WHERE user_id = ? 
			ORDER BY accessed_at DESC 
			LIMIT ?`
	} else {
		query = `SELECT id, task_id, user_id, token, action, accessed_at, ip_address 
			FROM task_access_log 
			WHERE user_id = $1 
			ORDER BY accessed_at DESC 
			LIMIT $2`
	}

	rows, err := db.conn.QueryContext(context.Background(), query, userID, limit)
	if err != nil {
		return nil, fmt.Errorf("failed to get audit log: %w", err)
	}
	defer func() {
		if err := rows.Close(); err != nil {
			log.Printf("ERROR: failed to close rows: %v", err)
		}
	}()

	return db.scanAuditLogEntries(rows)
}

// GetAuditLogForToken retrieves audit log entries for a specific token.
func (db *DB) GetAuditLogForToken(token string, limit int) ([]*AuditLogEntry, error) {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `SELECT id, task_id, user_id, token, action, accessed_at, ip_address 
			FROM task_access_log 
			WHERE token = ? 
			ORDER BY accessed_at DESC 
			LIMIT ?`
	} else {
		query = `SELECT id, task_id, user_id, token, action, accessed_at, ip_address 
			FROM task_access_log 
			WHERE token = $1 
			ORDER BY accessed_at DESC 
			LIMIT $2`
	}

	rows, err := db.conn.QueryContext(context.Background(), query, token, limit)
	if err != nil {
		return nil, fmt.Errorf("failed to get audit log: %w", err)
	}
	defer func() {
		if err := rows.Close(); err != nil {
			log.Printf("ERROR: failed to close rows: %v", err)
		}
	}()

	return db.scanAuditLogEntries(rows)
}

// scanAuditLogEntries scans rows into AuditLogEntry structs.
func (db *DB) scanAuditLogEntries(rows *sql.Rows) ([]*AuditLogEntry, error) {
	var entries []*AuditLogEntry
	for rows.Next() {
		var e AuditLogEntry
		var userID, token, ipAddress sql.NullString

		err := rows.Scan(&e.ID, &e.TaskID, &userID, &token, &e.Action, &e.AccessedAt, &ipAddress)
		if err != nil {
			return nil, fmt.Errorf("failed to scan audit log entry: %w", err)
		}

		if userID.Valid {
			e.UserID = &userID.String
		}
		if token.Valid {
			e.Token = &token.String
		}
		if ipAddress.Valid {
			e.IPAddress = &ipAddress.String
		}

		entries = append(entries, &e)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating audit log entries: %w", err)
	}

	return entries, nil
}

// DeleteOldAuditLogs removes audit log entries older than the retention period.
// This should be called by a nightly job.
func (db *DB) DeleteOldAuditLogs(retentionDays int) (int64, error) {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `DELETE FROM task_access_log 
			WHERE accessed_at < datetime('now', '-' || ? || ' days')`
	} else {
		query = `DELETE FROM task_access_log 
			WHERE accessed_at < NOW() - INTERVAL '1 day' * $1`
	}

	result, err := db.conn.ExecContext(context.Background(), query, retentionDays)
	if err != nil {
		return 0, fmt.Errorf("failed to delete old audit logs: %w", err)
	}

	affected, err := result.RowsAffected()
	if err != nil {
		return 0, fmt.Errorf("failed to get rows affected: %w", err)
	}

	return affected, nil
}

// CountAuditLogs returns the total number of audit log entries.
func (db *DB) CountAuditLogs() (int64, error) {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `SELECT COUNT(*) FROM task_access_log`
	} else {
		query = `SELECT COUNT(*) FROM task_access_log`
	}

	var count int64
	err := db.conn.QueryRowContext(context.Background(), query).Scan(&count)
	if err != nil {
		return 0, fmt.Errorf("failed to count audit logs: %w", err)
	}

	return count, nil
}

// GetOldestAuditLogDate returns the date of the oldest audit log entry.
func (db *DB) GetOldestAuditLogDate() (*time.Time, error) {
	var query string
	if db.dbType == DBTypeSQLite {
		query = `SELECT MIN(accessed_at) FROM task_access_log`
	} else {
		query = `SELECT MIN(accessed_at) FROM task_access_log`
	}

	var date sql.NullTime
	err := db.conn.QueryRowContext(context.Background(), query).Scan(&date)
	if err != nil {
		return nil, fmt.Errorf("failed to get oldest audit log date: %w", err)
	}

	if !date.Valid {
		return nil, nil
	}

	return &date.Time, nil
}