package v2stat

import (
	"context"
	"database/sql"
	"strings"
	"time"

	"github.com/sirupsen/logrus"
	"go.rikki.moe/v2stat/command"
	"google.golang.org/grpc"
)

type V2Stat struct {
	logger *logrus.Logger
	db     *sql.DB
	conn *grpc.ClientConn
	stat   command.StatsServiceClient
}

func NewV2Stat(logger *logrus.Logger, db *sql.DB, conn *grpc.ClientConn) *V2Stat {
	return &V2Stat{
		logger: logger,
		db:     db,
		conn:   conn,
		stat:   command.NewStatsServiceClient(conn),
	}
}

func (v *V2Stat) Close() {
	if v.db != nil {
		v.db.Close()
	}
	if v.conn != nil {
		v.conn.Close()
	}
}

func (v *V2Stat) SetConn(conn *grpc.ClientConn) {
	if v.conn != nil {
		v.conn.Close()
	}
	v.conn = conn
	v.stat = command.NewStatsServiceClient(conn)
}


func (v *V2Stat) InitDB() error {
	stmts := []string{
		`CREATE TABLE IF NOT EXISTS conn (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			type INTEGER NOT NULL,
			name TEXT NOT NULL,
			UNIQUE (type, name)
		);`,
		`CREATE TABLE IF NOT EXISTS stats (
			id INTEGER PRIMARY KEY AUTOINCREMENT,
			conn_id INTEGER NOT NULL,
			timestamp INTEGER NOT NULL,
			traffic INTEGER NOT NULL,
			direction INTEGER NOT NULL,
			FOREIGN KEY (conn_id) REFERENCES conn (id)
				ON DELETE CASCADE
				ON UPDATE CASCADE
		);`,
		`CREATE INDEX IF NOT EXISTS idx_conn_id ON stats (conn_id);`,
		`CREATE INDEX IF NOT EXISTS idx_timestamp ON stats (timestamp);`,
	}

	for _, stmt := range stmts {
		if _, err := v.db.Exec(stmt); err != nil {
			return err
		}
	}
	return nil
}

func (v *V2Stat) RecordNow(ctx context.Context) error {
	resp, err := v.stat.QueryStats(ctx, &command.QueryStatsRequest{
		Reset_: true,
	})
	if err != nil {
		v.logger.Errorf("Failed to query stats: %v", err)
		return err
	}

	tx, err := v.db.Begin()
	if err != nil {
		v.logger.Errorf("Failed to begin transaction: %v", err)
		return err
	}
	defer tx.Rollback() // safe to call even if already committed

	insertConnStmt, err := tx.Prepare(`INSERT OR IGNORE INTO conn (type, name) VALUES (?, ?)`)
	if err != nil {
		v.logger.Errorf("Failed to prepare conn insert statement: %v", err)
		return err
	}
	defer insertConnStmt.Close()

	selectConnIDStmt, err := tx.Prepare(`SELECT id FROM conn WHERE type = ? AND name = ?`)
	if err != nil {
		v.logger.Errorf("Failed to prepare conn select statement: %v", err)
		return err
	}
	defer selectConnIDStmt.Close()

	insertStatsStmt, err := tx.Prepare(`
		INSERT INTO stats (conn_id, timestamp, traffic, direction)
		VALUES (?, ?, ?, ?)
	`)
	if err != nil {
		v.logger.Errorf("Failed to prepare stats insert statement: %v", err)
		return err
	}
	defer insertStatsStmt.Close()

	for _, stat := range resp.Stat {
		connType, connName, direction, ok := parseStatKey(stat.Name)
		if !ok {
			v.logger.Warnf("Skipping unrecognized stat key: %s", stat.Name)
			continue
		}

		if _, err := insertConnStmt.Exec(connType, connName); err != nil {
			v.logger.Errorf("Failed to insert conn: %v", err)
			continue
		}

		var connID int
		err = selectConnIDStmt.QueryRow(connType, connName).Scan(&connID)
		if err != nil {
			v.logger.Errorf("Failed to retrieve conn_id: %v", err)
			continue
		}

		timeNow := time.Now().Unix()
		if _, err := insertStatsStmt.Exec(connID, timeNow, stat.Value, direction); err != nil {
			v.logger.Errorf("Failed to insert stats: %v", err)
			continue
		}

		v.logger.Infof("Inserted stats: conn_id=%d, timestamp=%d, traffic=%d, direction=%d", connID, timeNow, stat.Value, direction)
	}

	if err := tx.Commit(); err != nil {
		v.logger.Errorf("Failed to commit transaction: %v", err)
		return err
	}
	return nil
}

func parseStatKey(key string) (connType ConnectionType, connName string, direction TrafficDirection, ok bool) {
	parts := strings.Split(key, ">>>")
	if len(parts) != 4 || parts[2] != "traffic" {
		return 0, "", 0, false
	}

	switch parts[0] {
	case "user":
		connType = ConnTypeUser
	case "inbound":
		connType = ConnTypeInbound
	case "outbound":
		connType = ConnTypeOutbound
	default:
		return 0, "", 0, false
	}

	connName = parts[1]

	switch parts[3] {
	case "downlink":
		direction = DirectionDownlink
	case "uplink":
		direction = DirectionUplink
	default:
		return 0, "", 0, false
	}

	return connType, connName, direction, true
}

func (v *V2Stat) QueryConn() ([]ConnInfo, error) {
	rows, err := v.db.Query("SELECT type, name FROM conn")
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var conns []ConnInfo
	for rows.Next() {
		var conn ConnInfo
		if err := rows.Scan(&conn.Type, &conn.Name); err != nil {
			return nil, err
		}
		conns = append(conns, conn)
	}
	return conns, nil
}

func (v *V2Stat) QueryStatsHourly(conn *ConnInfo) ([]TrafficStat, error) {
	rows, err := v.db.Query(`
	SELECT
	  strftime('%Y-%m-%d %H:00:00', datetime(s.timestamp, 'unixepoch', '+8 hours')) AS time,
	  SUM(CASE WHEN s.direction = 0 THEN s.traffic ELSE 0 END) AS downlink,
	  SUM(CASE WHEN s.direction = 1 THEN s.traffic ELSE 0 END) AS uplink
	FROM stats s
	JOIN conn c ON s.conn_id = c.id
	WHERE c.type = ? AND c.name = ?
	GROUP BY time
	ORDER BY time;
`, conn.Type, conn.Name)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var stats []TrafficStat
	for rows.Next() {
		var s TrafficStat
		if err := rows.Scan(&s.Time, &s.Downlink, &s.Uplink); err != nil {
			panic(err)
		}
		stats = append(stats, s)
	}

	if err := rows.Err(); err != nil {
		return nil, err
	}
	return stats, nil		
}