using Strata.SqlTools.SqlBreakdown.Expressions.Conditional;
using SqlServerCommandVisitor = Strata.SqlTools.Visitors.SqlServer.CommandVisitor;

namespace Strata.SqlTools.Visitors.PostgreSql;

/// <summary>
/// Implements the visitor pattern to convert SQL expression objects into PostgreSQL-compatible SQL command strings.
/// Inherits from SqlServer.CommandVisitor and overrides only the dialect-specific formatting methods.
/// </summary>
public class CommandVisitor : SqlServerCommandVisitor
{
    private int _parameterIndex = 1;

    /// <summary>
    /// Formats an identifier for PostgreSQL using double-quote quoting.
    /// </summary>
    /// <param name="identifier">The identifier to format.</param>
    /// <returns>The quoted identifier.</returns>
    protected override string FormatIdentifier(string identifier) => $"\"{identifier}\"";

    /// <summary>
    /// Formats a parameter name for PostgreSQL using positional parameter syntax.
    /// Parameters in PostgreSQL are referenced as $1, $2, $3, etc.
    /// </summary>
    /// <param name="parameterName">The parameter name to format.</param>
    /// <returns>A SQL string in the format "$position" where position is a number.</returns>
    protected override string FormatParameterName(string parameterName)
    {
        // PostgreSQL uses positional parameters: $1, $2, $3, etc.
        return $"${_parameterIndex++}";
    }

    /// <summary>
    /// Formats a boolean literal for PostgreSQL using TRUE/FALSE keywords.
    /// </summary>
    /// <param name="value">The boolean value to format.</param>
    /// <returns>The string "true" or "false" in lowercase.</returns>
    protected override string FormatBooleanLiteral(bool value) => value ? "true" : "false";

    /// <summary>
    /// Formats a string literal for PostgreSQL with proper escaping of single quotes.
    /// </summary>
    /// <param name="value">The string value to format.</param>
    /// <returns>A SQL string literal enclosed in single quotes with escaped quotes.</returns>
    protected override string FormatStringLiteral(string value)
    {
        // PostgreSQL: escape single quotes by doubling them
        var escaped = value.Replace("'", "''");
        return $"'{escaped}'";
    }

    /// <summary>
    /// Formats a case-insensitive LIKE expression for PostgreSQL using ILIKE keyword.
    /// </summary>
    /// <param name="likeExpression">The LIKE expression to format.</param>
    /// <returns>A SQL string in the format "expression ILIKE pattern".</returns>
    protected override string FormatCaseInsensitiveLike(LikeExpression likeExpression)
    {
        return $"{likeExpression.Subject.Accept(this)} ILIKE {likeExpression.Pattern.Accept(this)}";
    }
}