using MultiversalDiplomacy.Model;

namespace MultiversalDiplomacy.Script;

/// <summary>
/// A script handler for modifying a game before it begins.
/// </summary>
public class SetupScriptHandler(Action<string> WriteLine, World world, bool strict = false) : IScriptHandler
{
    public string Prompt => "setup> ";

    public World World { get; private set; } = world;

    /// <summary>
    /// Whether unsuccessful commands should terminate the script.
    /// </summary>
    public bool Strict { get; } = strict;

    public IScriptHandler? HandleInput(string input)
    {
        var args = input.Split(' ', StringSplitOptions.RemoveEmptyEntries);
        if (args.Length == 0 || input.StartsWith('#'))
        {
            return this;
        }

        var command = args[0];
        switch (command)
        {
            case "help":
            case "?":
                WriteLine("commands:");
                WriteLine("  begin: complete setup and start the game (alias: ---)");
                WriteLine("  list <type>: list things in a game category");
                WriteLine("  option <name> <value>: set a game option");
                WriteLine("  unit <power> <type> <province> [location]: add a unit to the game");
                WriteLine("       <province> may be \"province/location\"");
                break;

            case "begin":
            case "---":
                WriteLine("Starting game");
                WriteLine("Ready for orders");
                return new GameScriptHandler(WriteLine, World, Strict);

            case "list" when args.Length == 1:
                WriteLine("usage:");
                WriteLine("  list powers: the powers in the game");
                WriteLine("  list units: units created so far");
                break;

            case "list" when args[1] == "powers":
                WriteLine("Powers:");
                foreach (string powerName in World.Powers)
                {
                    WriteLine($"  {powerName}");
                }
                break;

            case "list" when args[1] == "units":
                WriteLine("Units:");
                foreach (Unit unit in World.Units)
                {
                    WriteLine($"  {unit}");
                }
                break;

            case "option" when args.Length < 3:
                throw new NotImplementedException("There are no supported options yet");

            case "unit" when args.Length < 2:
                WriteLine("usage: unit [power] [type] [province]</location>");
                break;

            case "unit":
                string unitSpec = input["unit ".Length..];
                if (OrderParser.TryParseUnit(World, unitSpec, out Unit? newUnit)) {
                    World = World.Update(units: World.Units.Append(newUnit));
                    WriteLine($"Created {newUnit}");
                    return this;
                }
                WriteLine($"Could not match unit spec \"{unitSpec}\"");
                if (Strict) return null;
                break;

            default:
                WriteLine($"Unrecognized command: \"{command}\"");
                if (Strict) return null;
                break;
        }

        return this;
    }
}