package statistics

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

type DepsClick struct {
	Conn *sql.DB
}

type StatisticClick struct {
	conn *sql.DB
}

func NewClickStatistic(ctx context.Context, deps DepsClick) (*StatisticClick, error) {
	s := &StatisticClick{
		conn: deps.Conn,
	}

	err := s.checkMW(ctx)
	if err != nil {
		fmt.Println("error check material view existing")
		return nil, err
	}

	return s, nil
}

func (s *StatisticClick) checkMW(ctx context.Context) error {
	query := `
CREATE MATERIALIZED VIEW IF NOT EXISTS mv_last_answers_events
ENGINE = MergeTree()
PARTITION BY toStartOfDay(event_time)
ORDER BY (ctxsession, event_time) AS
SELECT
    event_time,ctxsession,ctxquizid,ctxquestionid,ctxidint,message,keyos,keydevice,keydevicetype,
    keybrowser,ctxuserip,ctxuserport,keydomain,keypath,ctxquiz,ctxreferrer
FROM statistics WHERE message IN ('InfoQuizOpen', 'InfoAnswer', 'InfoResult')
  AND event_level = 'info' AND create_time = (SELECT max(create_time) FROM statistics AS inner_table 
      WHERE inner_table.ctxsession = statistics.ctxsession);
`
	_, err := s.conn.ExecContext(ctx, query)
	if err != nil {
		return err
	}
	return nil
}

type PipeLineStatsResp [][]struct {
	Count      int64
	QuestionID int64
}

func (s *StatisticClick) GetPipelinesStatistics(ctx context.Context, from uint64, to uint64) ([]PipeLineStatsResp, error) {
	query := `
SELECT
    ctxsession,ctxquestionid,count(*) as session_count
FROM mv_last_answers_events WHERE event_time BETWEEN ? AND ?
GROUP BY ctxsession, ctxquestionid ORDER BY ctxsession, ctxquestionid
`
	rows, err := s.conn.QueryContext(ctx, query, from, to)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var pipelines []PipeLineStatsResp
	var currentPipeline PipeLineStatsResp
	var lastSession string

	for rows.Next() {
		var session string
		var questionID int64
		var count int64
		err := rows.Scan(&session, &questionID, &count)
		if err != nil {
			return nil, err
		}

		// новая сессия - новая воронка
		if session != lastSession && lastSession != "" {
			pipelines = append(pipelines, currentPipeline)
			currentPipeline = PipeLineStatsResp{}
		}

		// текущая статистика в текущую воронку
		currentPipeline = append(currentPipeline, []struct {
			Count      int64
			QuestionID int64
		}{{Count: count, QuestionID: questionID}})

		lastSession = session
	}

	// последня воронка если есть то добавляем
	if len(currentPipeline) > 0 {
		pipelines = append(pipelines, currentPipeline)
	}

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

	return pipelines, nil
}