package dbwrapper

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

	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/config"
	dbdialects "git.ksdemosapps.com/kylesoda/go-migrate/internal/app/db-wrapper/db_dialects"
	"git.ksdemosapps.com/kylesoda/go-migrate/internal/app/models"
	mssql "github.com/microsoft/go-mssqldb"
	"github.com/sirupsen/logrus"
)

func init() {
	Register(dbdialects.SqlServer, func() DbWrapper {
		return &mssqlDbWrapper{dialect: dbdialects.SqlServer}
	})
}

type mssqlRowResult struct {
	row *sql.Row
}

func (mr *mssqlRowResult) Scan(dest ...any) error {
	return mr.row.Scan(dest...)
}

type mssqlRowsResult struct {
	columns []string
	rows    *sql.Rows
}

func (mr *mssqlRowsResult) Close() error {
	return mr.rows.Close()
}

func (mr *mssqlRowsResult) Columns() ([]string, error) {
	if mr.columns != nil {
		return mr.columns, nil
	}

	return mr.rows.Columns()
}

func (mr *mssqlRowsResult) Err() error {
	return mr.rows.Err()
}

func (mr *mssqlRowsResult) Next() bool {
	return mr.rows.Next()
}

func (mr *mssqlRowsResult) Scan(dest ...any) error {
	return mr.rows.Scan(dest...)
}

func (mr *mssqlRowsResult) Values() ([]any, error) {
	columns, err := mr.Columns()
	if err != nil {
		return nil, err
	}

	rowValues := make([]any, len(columns))
	scanArgs := make([]any, len(columns))
	for i := range rowValues {
		scanArgs[i] = &rowValues[i]
	}

	if err := mr.rows.Scan(scanArgs...); err != nil {
		return nil, err
	}

	return rowValues, nil
}

type mssqlDbWrapper struct {
	db      *sql.DB
	dialect string
}

func (mw *mssqlDbWrapper) Connect(ctx context.Context, dbUrl string) error {
	db, err := sql.Open("sqlserver", dbUrl)
	if err != nil {
		return err
	}

	if err := db.PingContext(ctx); err != nil {
		if err := db.Close(); err != nil {
			return err
		}
		return err
	}

	mw.db = db
	return nil
}

func (mw *mssqlDbWrapper) Close() error {
	return mw.db.Close()
}

func (mw *mssqlDbWrapper) Exec(ctx context.Context, query string, args ...any) (ExecResult, error) {
	result, execErr := mw.db.ExecContext(ctx, query, args...)
	if execErr != nil {
		return ExecResult{}, execErr
	}

	affectedRows, err := result.RowsAffected()
	if err != nil {
		return ExecResult{}, err
	}

	return ExecResult{AffectedRows: affectedRows}, nil
}

func (mw *mssqlDbWrapper) GetDialect() string {
	return mw.dialect
}

func (mw *mssqlDbWrapper) Query(ctx context.Context, query string, args ...any) (RowsResult, error) {
	rows, err := mw.db.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, err
	}

	return &mssqlRowsResult{columns: nil, rows: rows}, nil
}

func (mw *mssqlDbWrapper) QueryRow(ctx context.Context, query string, args ...any) RowResult {
	row := mw.db.QueryRowContext(ctx, query, args...)
	return &mssqlRowResult{row: row}
}

func (mw *mssqlDbWrapper) SaveMassive(ctx context.Context, schema string, table string, columnNames []string, rows [][]any) (int64, error) {
	tx, err := mw.db.BeginTx(ctx, nil)
	if err != nil {
		return 0, err
	}

	fullTableName := fmt.Sprintf("[%s].[%s]", schema, table)

	stmt, err := tx.PrepareContext(ctx, mssql.CopyIn(fullTableName, mssql.BulkOptions{}, columnNames...))
	if err != nil {
		tx.Rollback()
		return 0, err
	}

	for _, row := range rows {
		_, err = stmt.ExecContext(ctx, row...)
		if err != nil {
			stmt.Close()
			tx.Rollback()
			return 0, err
		}
	}

	result, err := stmt.ExecContext(ctx)
	if err != nil {
		stmt.Close()
		tx.Rollback()
		return 0, err
	}

	if err := stmt.Close(); err != nil {
		tx.Rollback()
		return 0, err
	}

	if err := tx.Commit(); err != nil {
		return 0, err
	}

	rowsAffected, raErr := result.RowsAffected()
	if raErr != nil {
		return 0, nil
	}

	return rowsAffected, nil
}

func buildExtractQueryMssql(q ExtractionQuery) (string, error) {
	var sbQuery strings.Builder

	sbQuery.WriteString("SELECT ")

	hasRegularColumns := len(q.Columns) > 0
	hasJsonColumns := len(q.FromJsonColumns) > 0

	resolvedJson := make(map[string][]config.FromJsonItem, len(q.FromJsonColumns))
	if hasJsonColumns {
		for _, jsonConfig := range q.FromJsonColumns {
			actualColumnName, err := findColumnByPattern(q.Columns, jsonConfig.Column)
			if err != nil {
				return "", err
			}
			resolvedJson[actualColumnName] = append(resolvedJson[actualColumnName], jsonConfig)
		}
	}

	selectParts := make([]string, 0, len(q.Columns)+len(q.FromJsonColumns))
	if hasRegularColumns {
		for _, col := range q.Columns {
			jsonConfigs, isJsonColumn := resolvedJson[col.Name()]
			if isJsonColumn {
				for _, jsonConfig := range jsonConfigs {
					jsonPath := buildJsonPathMssql(jsonConfig.Field)
					jsonExpr := fmt.Sprintf("JSON_VALUE([%s], '%s') AS [%s]", col.Name(), jsonPath, col.Name())
					selectParts = append(selectParts, jsonExpr)
				}
				continue
			}

			colExpr := fmt.Sprintf("[%s]", col.Name())
			switch col.Type() {
			case "GEOMETRY":
				colExpr = fmt.Sprintf("[%s].STAsBinary() AS [%s]", col.Name(), col.Name())
			}
			selectParts = append(selectParts, colExpr)
		}
	} else if !hasJsonColumns {
		selectParts = append(selectParts, "*")
	}

	for i, part := range selectParts {
		sbQuery.WriteString(part)
		if i < len(selectParts)-1 {
			sbQuery.WriteString(", ")
		}
	}

	fmt.Fprintf(&sbQuery, " FROM [%s].[%s]", q.Schema, q.Table)

	if q.LowerLimit.IsValid || q.UpperLimit.IsValid {
		sbQuery.WriteString(" WHERE ")

		if q.LowerLimit.IsValid {
			fmt.Fprintf(&sbQuery, "[%s]", q.PrimaryKey)
			if q.LowerLimit.IsInclusive {
				sbQuery.WriteString(" >=")
			} else {
				sbQuery.WriteString(" >")
			}
			sbQuery.WriteString(" @min")
		}

		if q.LowerLimit.IsValid && q.UpperLimit.IsValid {
			sbQuery.WriteString(" AND ")
		}

		if q.UpperLimit.IsValid {
			fmt.Fprintf(&sbQuery, "[%s]", q.PrimaryKey)
			if q.UpperLimit.IsInclusive {
				sbQuery.WriteString(" <=")
			} else {
				sbQuery.WriteString(" <")
			}
			sbQuery.WriteString(" @max")
		}
	}

	fmt.Fprintf(&sbQuery, " ORDER BY [%s] ASC", q.PrimaryKey)

	return sbQuery.String(), nil
}

func findColumnByPattern(columns []models.ColumnType, pattern string) (string, error) {
	if pattern == "" {
		return "", fmt.Errorf("column pattern cannot be empty")
	}

	if before, ok := strings.CutSuffix(pattern, "*"); ok {
		prefix := before
		for _, col := range columns {
			if strings.HasPrefix(col.Name(), prefix) {
				return col.Name(), nil
			}
		}
		return "", fmt.Errorf("no column found matching pattern '%s'", pattern)
	}

	for _, col := range columns {
		if col.Name() == pattern {
			return col.Name(), nil
		}
	}
	return "", fmt.Errorf("column '%s' not found in table columns", pattern)
}

func (mw *mssqlDbWrapper) QueryFromObject(ctx context.Context, q ExtractionQuery) (RowsResult, error) {
	queryString, err := buildExtractQueryMssql(q)
	if err != nil {
		return nil, err
	}

	logrus.Debugf("Query: %s", queryString)

	var queryArgs []any

	if q.LowerLimit.IsValid {
		queryArgs = append(queryArgs, sql.Named("min", q.LowerLimit.Value))
	}

	if q.UpperLimit.IsValid {
		queryArgs = append(queryArgs, sql.Named("max", q.UpperLimit.Value))
	}

	return mw.Query(ctx, queryString, queryArgs...)
}

func buildJsonPathMssql(field string) string {
	if len(field) > 0 && field[0] == '.' {
		field = field[1:]
	}

	return "$." + field
}