scritcher/src/lang.zig

const std = @import("std");

const plugin = @import("plugin.zig");

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

pub const CommandType = enum {
    Noop,
    Load,
    Quicksave,

    Amp,
    RFlanger,
    Eq,
    Phaser,
    Mbeq,
    Chorus,
    PitchScaler,
    Reverb,
};

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 consumePosition(self: *const Command) !plugin.Position {
        return plugin.Position{
            .split = try self.usizeArgAt(0),
            .index = try self.usizeArgAt(1),
        };
    }

    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 fn floatArgMany(
        self: *const Command,
        allocator: *std.mem.Allocator,
        start_index: usize,
        elements: usize,
        default: f32,
    ) ![]const f32 {
        var i: usize = start_index;
        var arr = std.ArrayList(f32).init(allocator);

        while (i < elements) : (i += 1) {
            var value: f32 = self.floatArgAt(i) catch |err| blk: {
                std.debug.warn("\tdoing default on arg {}\n", i);
                break :blk default;
            };

            try arr.append(value);
        }

        return arr.toSliceConst();
    }

    pub fn appendParam(
        self: *const Command,
        params: *plugin.ParamList,
        symbol: []const u8,
        idx: usize,
    ) !void {
        var val = try self.floatArgAt(idx);
        try params.append(plugin.Param{
            .sym = symbol,
            .value = val,
        });
    }
};

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

pub const PluginKeywords = [_]CommandType{ .Amp, .RFlanger };
pub const KeywordMap = std.AutoHashMap([]const u8, CommandType);

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

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

    fn fillKeywords(self: *Lang) !void {
        _ = try self.keywords.put("noop", .Noop);
        _ = try self.keywords.put("load", .Load);
        _ = try self.keywords.put("quicksave", .Quicksave);

        _ = try self.keywords.put("amp", .Amp);
        _ = try self.keywords.put("rflanger", .RFlanger);
        _ = try self.keywords.put("eq", .Eq);
        _ = try self.keywords.put("mbeq", .Mbeq);
        _ = try self.keywords.put("phaser", .Phaser);
        _ = try self.keywords.put("chorus", .Chorus);
        _ = try self.keywords.put("pitchscaler", .PitchScaler);
        _ = try self.keywords.put("reverb", .Reverb);
    }

    pub fn parse(self: *Lang, data: []const u8) !CommandList {
        var splitted_it = std.mem.separate(data, ";");
        try self.fillKeywords();
        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 kv_opt = self.keywords.get(command);
            var ctype: CommandType = undefined;
            if (kv_opt) |kv| {
                ctype = kv.value;
            } else {
                std.debug.warn("Unknown command: '{}'\n", command);
                return ParseError.UnknownCommand;
            }

            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