package main

import (
	"encoding/csv"
	"io"
	"os"
	"strconv"
	"strings"

	"zombiezen.com/go/sqlite"
	"zombiezen.com/go/sqlite/sqlitex"
)

const latestData = "./data/D_Bahnhof_2020_alle.CSV"

const (
	rowId   = 1
	rowName = 3
	rowLat  = 6
	rowLon  = 5
)

func parseData() (*sqlite.Conn, error) {
	// Open data file
	dataFile, err := os.Open(latestData)
	if err != nil {
		return nil, err
	}
	defer dataFile.Close()
	// Create in-memory sqlite database
	db, err := createDB()
	if err != nil {
		return nil, err
	}
	// Read csv
	r := csv.NewReader(dataFile)
	r.Comma = ';'
	i := 0
	for {
		record, err := r.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			return nil, err
		}
		// Skip header
		i++
		if i == 1 {
			continue
		}
		// Insert data
		lat, err := strconv.ParseFloat(strings.ReplaceAll(record[rowLat], ",", "."), 64)
		if err != nil {
			return nil, err
		}
		lon, err := strconv.ParseFloat(strings.ReplaceAll(record[rowLon], ",", "."), 64)
		if err != nil {
			return nil, err
		}
		err = sqlitex.Exec(db, "INSERT INTO stations (id, name, lat, lon) VALUES (?, ?, ?, ?)", nil, record[rowId], record[rowName], lat, lon)
		if err != nil {
			return nil, err
		}
	}
	// Finished
	return db, nil
}

type station struct {
	id   string
	name string
	lat  float64
	lon  float64
}

func findStations(db *sqlite.Conn, name string) (stations []*station, err error) {
	err = sqlitex.Exec(db, "select id, name, lat, lon from stations where id = ? or ( name like '%' || ? || '%' and ? not in ( select id from stations ) ) order by name asc", func(stmt *sqlite.Stmt) error {
		stations = append(stations, &station{
			id:   stmt.ColumnText(0),
			name: stmt.ColumnText(1),
			lat:  stmt.ColumnFloat(2),
			lon:  stmt.ColumnFloat(3),
		})
		return nil
	}, name, name, name)
	if err != nil {
		return nil, err
	}
	return stations, nil
}