using System.Collections;
using System.Text;
using System.Text.RegularExpressions;
using Strata.SqlTools.SqlBreakdown.Classes;
using Strata.SqlTools.Statements.SqlServer;

namespace Strata.SqlTools.Breakdowns.SqlServer;

/// <summary>
/// Represents a SQL Server stored procedure call breakdown with procedure name and parameters.
/// </summary>
public class ProcedureBreakdown : SqlBreakdownBase
{
    protected readonly StatementParser Parser;

    /// <summary>
    /// Initializes a new instance of the <see cref="ProcedureBreakdown"/> class.
    /// </summary>
    public ProcedureBreakdown()
    {
        Parser = new StatementParser();
        ProcedureName = new SqlClause();
        Parameters = [];
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="ProcedureBreakdown"/> class.
    /// </summary>
    /// <param name="procedureName">The stored procedure name.</param>
    public ProcedureBreakdown(string procedureName) : this()
    {
        var cleanName = Parser.ExtractSqlComments(procedureName, out var nameComments);
        ProcedureName.Clause = cleanName.Trim();
        ProcedureName.Comment = nameComments.Count > 0 ? string.Join(" ", nameComments) : null;
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="ProcedureBreakdown"/> class.
    /// </summary>
    /// <param name="procedureName">The stored procedure name.</param>
    /// <param name="parameters">The parameters dictionary (parameter name -> value expression).</param>
    public ProcedureBreakdown(string procedureName, Dictionary<string, string> parameters) : this(procedureName)
    {
        Parameters = parameters ?? [];
    }

    /// <summary>
    /// Gets or sets the stored procedure name.
    /// </summary>
    public SqlClause ProcedureName { get; set; }

    /// <summary>
    /// Gets or sets the parameters dictionary (parameter name -> value expression).
    /// </summary>
    public Dictionary<string, string> Parameters { get; set; }

    /// <summary>
    /// Gets a value indicating whether parameters are being used.
    /// </summary>
#pragma warning disable S2325 // Methods and properties that don't access instance data should be static
    public bool IsUsingParameters => Parameters.Count > 0;
#pragma warning restore S2325

    /// <summary>
    /// Adds a parameter to the stored procedure call.
    /// </summary>
    /// <param name="parameterName">The parameter name (with or without @).</param>
    /// <param name="valueExpression">The value expression or literal.</param>
#pragma warning disable S2325 // Methods and properties that don't access instance data should be static
    public void AddParameter(string parameterName, string valueExpression)
#pragma warning restore S2325
    {
        if (string.IsNullOrWhiteSpace(parameterName))
        {
            throw new ArgumentNullException(nameof(parameterName));
        }

        // Ensure parameter name starts with @
        if (!parameterName.StartsWith('@'))
        {
            parameterName = "@" + parameterName;
        }

        Parameters[parameterName] = valueExpression;
    }

    /// <summary>
    /// Gets the SQL breakdown as a string.
    /// </summary>
    /// <returns>The EXECUTE/EXEC SQL statement.</returns>
    protected override string GetSqlBreakdown()
    {
        var sb = new StringBuilder();

        sb.Append("EXEC ");
        sb.Append(ProcedureName.Clause);

        if (IsUsingParameters)
        {
            sb.AppendLine();
            var paramList = new List<string>();
            foreach (var param in Parameters)
            {
                paramList.Add($"    {param.Key} = {param.Value}");
            }
            sb.Append(string.Join($",{Environment.NewLine}", paramList));
        }

        return sb.ToString();
    }

    #region Parse Methods

    /// <summary>
    /// Parses an EXEC/EXECUTE SQL statement into a ProcedureBreakdown object.
    /// </summary>
    /// <param name="sql">The EXEC/EXECUTE SQL statement to parse.</param>
    /// <returns>A ProcedureBreakdown object representing the parsed statement.</returns>
    /// <exception cref="ArgumentNullException">Thrown when sql is null or empty.</exception>
    /// <exception cref="FormatException">Thrown when the SQL statement cannot be parsed.</exception>
    public static ProcedureBreakdown Parse(string sql)
    {
        if (string.IsNullOrWhiteSpace(sql))
        {
            throw new ArgumentNullException(nameof(sql), "SQL statement cannot be null or empty.");
        }

        if (!TryParse(sql, out var result, out var error))
        {
            throw new FormatException($"Failed to parse EXEC statement: {error}");
        }

        return result;
    }

    /// <summary>
    /// Attempts to parse an EXEC/EXECUTE SQL statement into a ProcedureBreakdown object.
    /// </summary>
    /// <param name="sql">The EXEC/EXECUTE SQL statement to parse.</param>
    /// <param name="result">When this method returns, contains the parsed ProcedureBreakdown if successful, or null if parsing failed.</param>
    /// <returns>true if the SQL was successfully parsed; otherwise, false.</returns>
    public static bool TryParse(string sql, out ProcedureBreakdown result)
        => TryParse(sql, out result, out _);

    /// <summary>
    /// Attempts to parse an EXEC/EXECUTE SQL statement into a ProcedureBreakdown object.
    /// </summary>
    /// <param name="sql">The EXEC/EXECUTE SQL statement to parse.</param>
    /// <param name="result">When this method returns, contains the parsed ProcedureBreakdown if successful, or null if parsing failed.</param>
    /// <param name="errorMessage">When this method returns false, contains a message describing why parsing failed.</param>
    /// <returns>true if the SQL was successfully parsed; otherwise, false.</returns>
    public static bool TryParse(string sql, out ProcedureBreakdown result, out string errorMessage)
    {
        result = null!;
        errorMessage = null!;

        try
        {
            if (!ParsePreparation.TryRunPrelude(
                    sql, new StatementParser(), @"^\s*(EXEC|EXECUTE)\b", "EXEC or EXECUTE",
                    out sql, out var setupClauses, out var finishClauses, out errorMessage))
            {
                return false;
            }

            // Parse EXEC statement - match procedure name and parameters
            // Pattern: EXEC[UTE] procedureName [@param = value, ...]
            var execMatch = Regex.Match(sql,
                @"(?:EXEC|EXECUTE)\s+([^\s@,]+)(?:\s+(.*))?$",
                RegexOptions.IgnoreCase | RegexOptions.Singleline, Strata.SqlTools.SqlBreakdown.Utilities.RegexDefaults.MatchTimeout);

            if (!execMatch.Success)
            {
                errorMessage = "Could not parse EXEC statement. Expected format: EXEC procedureName [@param = value, ...]";
                return false;
            }

            var procedureName = execMatch.Groups[1].Value.Trim();
            var parametersText = execMatch.Groups.Count > 2 ? execMatch.Groups[2].Value.Trim() : string.Empty;

            var parameters = new Dictionary<string, string>();

            if (!string.IsNullOrWhiteSpace(parametersText))
            {
                // Parse parameters - handle both @param = value and positional parameters
                var paramMatches = Regex.Matches(parametersText,
                    @"(@\w+)\s*=\s*([^,]+)(?:,|$)",
                    RegexOptions.IgnoreCase, Strata.SqlTools.SqlBreakdown.Utilities.RegexDefaults.MatchTimeout);

                parameters = paramMatches
                    .Cast<System.Text.RegularExpressions.Match>()
                    .ToDictionary(
                        paramMatch => paramMatch.Groups[1].Value.Trim(),
                        paramMatch => paramMatch.Groups[2].Value.Trim()
                    );
            }

            result = new ProcedureBreakdown(procedureName, parameters)
            {
                SetupClauses = setupClauses,
                FinishClauses = finishClauses
            };

            return true;
        }
        catch (Exception ex)
        {
            errorMessage = $"Unexpected error during parsing: {ex.Message}";
            return false;
        }
    }

    #endregion
}