const std = @import("std");

pub const ParseError = error{
    NoCommandGiven,
    UnknownCommand,
    ArgRequired,
};

pub const CommandType = enum {
    Noop,
    Load,
    Amp,
    Quicksave,
};

pub const Command = struct {
    command: CommandType,
    args: ArgList,

    pub fn print(self: *const Command) void {
        std.debug.warn("cmd:{}\n", self.command);
    }

    pub fn argAt(self: *const Command, idx: usize) ![]const u8 {
        const args = self.args.toSliceConst();

        if (idx > (args.len - 1)) {
            std.debug.warn("Expected argument at index {}\n", idx);
            return ParseError.ArgRequired;
        }

        return args[idx];
    }

    pub fn usizeArgAt(self: *const Command, idx: usize) !usize {
        var arg = try self.argAt(idx);
        return try std.fmt.parseInt(usize, arg, 10);
    }

    pub fn intArgAt(self: *const Command, idx: usize) !i32 {
        var arg = try self.argAt(idx);
        return try std.fmt.parseInt(i32, arg, 10);
    }

    pub fn floatArgAt(self: *const Command, idx: usize) !f32 {
        var arg = try self.argAt(idx);
        return try std.fmt.parseFloat(f32, arg);
    }
};

pub const CommandList = std.ArrayList(*Command);
pub const ArgList = std.ArrayList([]const u8);

pub fn commandToCmdType(command: []const u8) ParseError!CommandType {
    if (std.mem.eql(u8, command, "noop")) {
        return CommandType.Noop;
    } else if (std.mem.eql(u8, command, "load")) {
        return CommandType.Load;
    } else if (std.mem.eql(u8, command, "amp")) {
        return CommandType.Amp;
    } else if (std.mem.eql(u8, command, "quicksave")) {
        return CommandType.Quicksave;
    } else {
        std.debug.warn("Unknown command: '{}'\n", command);
        return ParseError.UnknownCommand;
    }
}

pub const Lang = struct {
    allocator: *std.mem.Allocator,

    pub fn init(allocator: *std.mem.Allocator) Lang {
        return Lang{ .allocator = allocator };
    }

    pub fn parse(self: *Lang, data: []const u8) !CommandList {
        var splitted_it = std.mem.separate(data, ";");
        var cmds = CommandList.init(self.allocator);

        while (splitted_it.next()) |stmt_orig| {
            var stmt = std.mem.trimRight(u8, stmt_orig, "\n");
            stmt = std.mem.trimLeft(u8, stmt, "\n");

            if (stmt.len == 0) continue;
            if (stmt[0] == '#') continue;

            // TODO better tokenizer instead of just tokenize(" ");
            var tok_it = std.mem.tokenize(stmt, " ");

            var cmd_opt = tok_it.next();
            if (cmd_opt == null) return ParseError.NoCommandGiven;

            var command = cmd_opt.?;
            var ctype = try commandToCmdType(command);
            var args = ArgList.init(self.allocator);

            while (tok_it.next()) |arg| {
                try args.append(arg);
            }

            // construct final Command based on command
            var cmd_ptr = try self.allocator.create(Command);
            cmd_ptr.* = Command{ .command = ctype, .args = args };
            try cmds.append(cmd_ptr);
        }

        return cmds;
    }
};

// TODO tests