package main

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

// mysqlCol returns a quoted column name if present, otherwise a SQL literal/expression fallback.
func mysqlCol(ctx context.Context, db *sql.DB, table, column, fallbackExpr string) string {
	if mysqlColumnExists(ctx, db, table, column) {
		q, err := quoteMySQLIdent(column)
		if err != nil {
			return fallbackExpr
		}
		return q
	}
	return fallbackExpr
}

// mysqlCoalesce returns COALESCE(column, fallback) when column exists, else fallback alone.
func mysqlCoalesce(ctx context.Context, db *sql.DB, table, column, fallbackExpr string) string {
	if mysqlColumnExists(ctx, db, table, column) {
		q, err := quoteMySQLIdent(column)
		if err != nil {
			return fallbackExpr
		}
		return fmt.Sprintf("COALESCE(%s, %s)", q, fallbackExpr)
	}
	return fallbackExpr
}

// mysqlSelectList builds "SELECT a, b, ..." from expressions (already resolved).
func mysqlSelectList(exprs ...string) string {
	return "SELECT " + strings.Join(exprs, ", ")
}

// scanIntish scans MySQL INT/DECIMAL/string numeric values into an int.
func scanIntish(v any) int {
	switch x := v.(type) {
	case int64:
		return int(x)
	case int32:
		return int(x)
	case float64:
		return int(x)
	case []byte:
		var n float64
		if _, err := fmt.Sscanf(string(x), "%f", &n); err == nil {
			return int(n)
		}
	case string:
		var n float64
		if _, err := fmt.Sscanf(x, "%f", &n); err == nil {
			return int(n)
		}
	}
	return 0
}

// queryFirstOK tries queries in order until one succeeds (for column-shape fallbacks).
func queryFirstOK(ctx context.Context, db *sql.DB, queries ...string) (*sql.Rows, error) {
	var last error
	for _, q := range queries {
		rows, err := db.QueryContext(ctx, q)
		if err == nil {
			return rows, nil
		}
		last = err
	}
	if last == nil {
		return nil, fmt.Errorf("no queries provided")
	}
	return nil, last
}