using System;
using System.Linq;
using System.Text.RegularExpressions;

namespace DbMigrate {
    internal static class Extensions {
        public static string[] GetCommonColumns(this SqlTable table, SqlTable table2) {
            return table.GetColumnNames().Where(f => table2.HasColumn(f)).ToArray();
        }

        public static void ParseSql(this SqlTable table, string sql, string tableName = null) {
            if (tableName != null) {
                table.TableName = tableName;
            }

            bool inTable = false;
            bool inColumns = false;




            Match m = null;
            foreach (string line in Regex.Split(sql, "\\r\\n")) {
                if (string.IsNullOrEmpty(line) || line.StartsWith("--")) {
                    continue;
                }

                m = Regex.Match(line, "^CREATE TABLE( IF NOT EXISTS)? (\\S+) ");
                if (m.Success) {
                    if (string.IsNullOrEmpty(tableName) && string.IsNullOrEmpty(table.TableName)) {
                        // Set table name from the above regex match
                        table.TableName = m.Groups[2].Value.Trim();
                    }
                    if (!inTable && (table.TableName == null || m.Groups[2].Value.Trim() == table.TableName)) {
                        table.CreateTableSql += line + Environment.NewLine;
                        inTable = true;
                        inColumns = true;
                        continue;
                    } else {
                        if (inTable) {
                            // We are done with this table
                            return;
                        }
                        continue;
                    }
                }

                m = Regex.Match(line, "^CREATE INDEX( IF NOT EXISTS)? (\\S+) ");
                if (m.Success && inTable) {
                    table.Indexes.Add(m.Groups[2].Value.Trim(), line.Trim());
                    continue;
                }

                m = Regex.Match(line, "^CREATE TRIGGER( IF NOT EXISTS)? (\\S+) ");
                if (m.Success && inTable) {
                    table.Triggers.Add(m.Groups[2].Value.Trim(), line.Trim());
                    continue;
                }

                if (inColumns) {
                    if (line.Trim().StartsWith(")")) {
                        inColumns = false;
                    } else {
                        m = Regex.Match(line.Trim(), "^(\\S+).*");
                        if (m.Success) {
                            string columnLine = line.Trim();
                            if (columnLine.EndsWith(",")) {
                                columnLine = columnLine.Substring(0, columnLine.Length - 1);
                            }
                            table.Columns.Add(m.Groups[1].Value.Trim(), columnLine);
                        }
                    }
                }

                table.CreateTableSql += line + Environment.NewLine;
            }
        }
    }
}