package main

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
	log "github.com/sirupsen/logrus"
)

func main() {
	log.SetFormatter(&log.TextFormatter{
		FullTimestamp:   true,
		TimestampFormat: time.StampMilli,
	})
	log.SetLevel(log.DebugLevel)

	log.Info("Starting migration...")

	ctxSource, cancel := context.WithTimeout(context.Background(), 20*time.Second)
	defer cancel()

	sourcePool, err := db.Connect(ctxSource, config.App.FromDb.Url)
	defer db.Close(sourcePool)
	if err != nil {
		log.Fatal(err)
	}
	log.Info("Successfully connected to from_db")

	ctxTarget, cancel := context.WithTimeout(context.Background(), 20*time.Second)
	defer cancel()

	targetPool, err := db.Connect(ctxTarget, config.App.ToDb.Url)
	defer db.Close(targetPool)
	if err != nil {
		log.Fatal(err)
	}
	log.Info("Successfully connected to to_db")

	schema := "test"
	table := "migration_test"
	colNames := []string{"id", "nombre_producto", "descripcion", "stock", "precio", "es_activo", "fecha_creacion", "ultima_actualizacion", "configuracion_json", "etiquetas", "binario_test", "ip_servidor", "rango_prueba"}

	rowValues, err := extractData(ctxSource, sourcePool, schema, table, colNames, 2)

	if err != nil {
		log.Fatal("Unexpected error when extracting data", err)
	}

	for index, row := range rowValues {
		log.Debugf("Values for row %d", index+1)
		for i, v := range row {
			log.Debugf("%s: %v", colNames[i], v)
		}
	}

	insertedRows, err := insertData(ctxTarget, targetPool, schema, table, colNames, rowValues)
	if err != nil {
		log.Fatal("Unexpected error when inserting rows: ", err)
	}

	log.Infof("Inserted rows: %d", insertedRows)

	log.Info("Migration completed successfully!")
}

func buildExtractSqlSentence(schema, table string, colNames []string) string {
	var sbColumns strings.Builder

	for i, col := range colNames {
		sbColumns.WriteString(`"`)
		sbColumns.WriteString(col)
		sbColumns.WriteString(`"`)
		if i < len(colNames)-1 {
			sbColumns.WriteString(", ")
		}
	}

	return fmt.Sprintf(`SELECT %s FROM "%s"."%s" LIMIT $1`, sbColumns.String(), schema, table)
}

func extractData(ctx context.Context, sourcePool *pgxpool.Pool, schema string, table string, colNames []string, limit int) ([][]any, error) {
	if len(colNames) == 0 {
		return nil, errors.New("Empty column names received")
	}

	sql := buildExtractSqlSentence(schema, table, colNames)

	log.Debug("Executing query: ", sql)

	rows, err := sourcePool.Query(ctx, sql, limit)
	if err != nil {
		if !errors.Is(err, pgx.ErrNoRows) {
			return nil, fmt.Errorf("Unexpected error: %w", err)
		}

		log.Warn("Unexpected error", err)
		return [][]any{}, nil
	}
	defer rows.Close()

	cols := rows.FieldDescriptions()
	for _, c := range cols {
		log.Debugf("Column: %+v", c)
	}

	rowValues := make([][]any, 0, limit)

	for rows.Next() {
		values := make([]any, len(cols))
		valuePtrs := make([]any, len(cols))

		for i := range values {
			valuePtrs[i] = &values[i]
		}

		rows.Scan(valuePtrs...)

		rowValues = append(rowValues, values)
	}

	return rowValues, nil
}

func insertData(ctx context.Context, targetPool *pgxpool.Pool, schema string, table string, colNames []string, rowValues [][]any) (int64, error) {
	identifier := pgx.Identifier{schema, table}

	count, err := targetPool.CopyFrom(
		ctx,
		identifier,
		colNames,
		pgx.CopyFromRows(rowValues),
	)

	if err != nil {
		return 0, fmt.Errorf("error en CopyFrom: %w", err)
	}

	return count, nil
}

func Map[T any, V any](input []T, mapper func(T) V) []V {
	result := make([]V, len(input))

	for i, v := range input {
		result[i] = mapper(v)
	}

	return result
}