using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text.Json;
using System.CommandLine.DragonFruit;
using System.Linq;
using System.Text.Json.Serialization;
using CsvHelper;

namespace BunyMuny {
	internal class Program {
		/// <summary>
		/// BunyMuny parses the CSV output of various bank statement listings and converts it to something more human readable with nice visualisations.
		/// </summary>
		/// <param name="file">The CSV file to read</param>
		/// <param name="ruleFile">The JSON file to use for rules when parsing statement descriptions</param>
		/// <returns></returns>
		private static int Main(string file = "test.csv", string ruleFile = "rules.json") {
			var bank = Bank.Other;
			var statements = new List<Statement>();
			List<Rule> rules;

			using (var ruleStreamReader = new StreamReader(ruleFile)) {
				var jsonOptions = new JsonSerializerOptions();
				jsonOptions.Converters.Add(new JsonStringEnumConverter(JsonNamingPolicy.CamelCase));
				jsonOptions.WriteIndented = true;
				rules = JsonSerializer.Deserialize<List<Rule>>(ruleStreamReader.ReadToEnd(), jsonOptions);
			}

			using var sr = new StreamReader(file);
			using var csv = new CsvReader(sr, CultureInfo.InvariantCulture);

			csv.Read();
			csv.ReadHeader();

			// get the first line of the CSV file (the header) as a string
			var header = csv.Parser.Context.RawRecord.Trim();
			switch (header) {
				case null:
					Console.WriteLine("File is empty 0uo");
					return 1;
				case "Date,Description,Debits and credits,Balance":
					bank = Bank.ME;
					break;
				case "Whatever NAB uses I guess":
					bank = Bank.NAB;
					break;
				default:
					Console.WriteLine($"Unknown header: [{header}]");
					break;
			}

			while (csv.Read()) {
				switch (bank) {
					case Bank.ME:
						var value = double.Parse(csv.GetField("Debits and credits").TrimStart().Replace("$", ""));
						// SHOW PET THIS
						var ruleValues = MatchAgainstRules(rules, csv.GetField("Description"));

						statements.Add(new Statement() {
							Date = DateTime.ParseExact(csv.GetField("Date"), "dd/MM/yyyy", CultureInfo.InvariantCulture),
							OriginalDescription = csv.GetField("Description"),
							Description = ruleValues.Description,
							Category = ruleValues.Category,
							Value = value
						});
						break;

					case Bank.NAB:
						Console.WriteLine("Unimplemented");
						return 1;

					case Bank.Other:
						Console.WriteLine("Unknown bank!");
						return 1;

					default:
						Console.WriteLine(":(");
						return 1;
				}
			}

			foreach (var statement in statements.
				Where(s => s.Category != null).
				OrderBy(s => s.Date)) {
				Console.WriteLine(statement);
			}

			return 0;
		}

		private static (string Category, string Description) MatchAgainstRules(List<Rule> rules, string value) {
			foreach (var rule in rules) {
				if (rule.Check(value)) {
					return (rule.Category, rule.Description);
				}
			}

			return (null, null);
		}
	}
}