const std = @import("std");

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

pub const ParseError = error{
    OutOfMemory,
    ArgRequired,
    ParseFail,
};

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

    Amp,
    RFlanger,
    Eq,
    Phaser,
    Mbeq,
    Chorus,
    PitchScaler,
    Reverb,
    Highpass,
    Delay,
    Vinyl,
    RevDelay,
    Gate,
    Detune,
    Overdrive,
    Degrade,
    RePsycho,
    TalkBox,
    DynComp,
    ThruZero,
    Foverdrive,
    Gverb,
    Invert,
    TapeDelay,
    ModDelay,
    MultiChorus,

    Noise,
    WildNoise,
    Write,
    Embed,

    Rotate,
};

pub const Command = struct {
    command: CommandType,
    args: ArgList,
    cur_idx: usize = 0,

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

    pub fn argAt(self: Command, idx: usize) ![]const u8 {
        std.debug.warn("{} {}", .{ idx, self.args.len });

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

        const args = self.args.toSliceConst();
        return args[idx];
    }

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

    pub fn consumePosition(self: *Command) !plugin.Position {
        self.cur_idx = 2;
        return plugin.Position{
            .split = try self.usizeArgAt(0),
            .index = try self.usizeArgAt(1),
        };
    }

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

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

    pub fn floatArgMany(
        self: 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: *Command,
        params: *plugin.ParamList,
        symbol: []const u8,
    ) !void {
        var val = try self.floatArgAt(self.cur_idx);
        self.cur_idx += 1;

        try params.append(plugin.Param{
            .sym = symbol,
            .value = val,
        });
    }

    pub fn appendParamMap(
        self: *Command,
        map: *plugin.ParamMap,
        symbol: []const u8,
    ) !void {
        var val = try self.floatArgAt(self.cur_idx);
        self.cur_idx += 1;
        _ = try map.put(symbol, val);
    }

    pub fn copy(self: Command, allocator: *std.mem.Allocator) !*Command {
        var cmd = try allocator.create(Command);
        cmd.* = Command{
            .command = self.command,
            .args = self.args,
            .cur_idx = self.cur_idx,
        };

        return cmd;
    }
};

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

pub const KeywordMap = std.StringHashMap(CommandType);

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

    has_error: bool = false,
    line: usize = 0,

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

    pub fn deinit(self: *Lang) void {
        self.keywords.deinit();
    }

    pub fn reset(self: *Lang) void {
        self.has_error = false;
        self.line = 0;
    }

    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("runqs", .RunQS);

        _ = 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);
        _ = try self.keywords.put("highpass", .Highpass);
        _ = try self.keywords.put("delay", .Delay);
        _ = try self.keywords.put("vinyl", .Vinyl);
        _ = try self.keywords.put("revdelay", .RevDelay);
        _ = try self.keywords.put("gate", .Gate);
        _ = try self.keywords.put("detune", .Detune);
        _ = try self.keywords.put("overdrive", .Overdrive);
        _ = try self.keywords.put("talkbox", .TalkBox);
        _ = try self.keywords.put("thruzero", .ThruZero);
        _ = try self.keywords.put("foverdrive", .Foverdrive);
        _ = try self.keywords.put("gverb", .Gverb);
        _ = try self.keywords.put("invert", .Invert);
        _ = try self.keywords.put("tapedelay", .TapeDelay);
        _ = try self.keywords.put("moddelay", .ModDelay);
        _ = try self.keywords.put("multichorus", .MultiChorus);

        // custom implementations (not lv2)
        _ = try self.keywords.put("noise", .Noise);
        _ = try self.keywords.put("wildnoise", .WildNoise);
        _ = try self.keywords.put("write", .Write);
        _ = try self.keywords.put("embed", .Embed);
        _ = try self.keywords.put("degrade", .Degrade);
        _ = try self.keywords.put("repsycho", .RePsycho);
        _ = try self.keywords.put("dyncomp", .RePsycho);

        // even more custom
        _ = try self.keywords.put("rotate", .Rotate);
    }

    pub fn getCommand(self: *Lang, stmt: []const u8) ?CommandType {
        var kv_opt = self.keywords.get(stmt);

        if (kv_opt) |kv| {
            return kv.value;
        } else {
            return null;
        }
    }

    fn expectAny(self: *Lang, count: usize, args: ArgList) !void {
        if (args.len != count) {
            self.doError("expected {} arguments, found {}", .{ count, args.len });
            return error.ArgRequired;
        }
    }

    fn expectSingle(self: *Lang, args: ArgList) !void {
        return try self.expectAny(1, args);
    }

    fn expectFloat(self: *Lang, count: usize, args: ArgList) !void {
        var i: usize = 0;

        if (args.len != count) {
            self.doError("expected {} arguments, found {}", .{ count, args.len });
            return error.ArgRequired;
        }

        while (i < count) : (i += 1) {
            var arg = args.at(i);

            _ = std.fmt.parseFloat(f32, arg) catch |err| {
                std.debug.warn("failed to parse f32: {}\n", .{err});
                return error.FloatParseFail;
            };
        }
    }

    fn validateCommand(self: *Lang, cmd: Command) !void {
        switch (cmd.command) {
            .Quicksave, .Noop => {},
            .Load, .RunQS => try self.expectSingle(cmd.args),
            .Amp => try self.expectFloat(3, cmd.args),
            .RFlanger => try self.expectFloat(4, cmd.args),
            .Eq => try self.expectFloat(5, cmd.args),
            .Phaser => try self.expectFloat(6, cmd.args),
            .Mbeq => try self.expectFloat(17, cmd.args),
            .Chorus => try self.expectFloat(8, cmd.args),
            .PitchScaler => try self.expectFloat(3, cmd.args),
            .Reverb => try self.expectFloat(12, cmd.args),
            .Highpass => try self.expectFloat(5, cmd.args),
            .Delay => try self.expectFloat(12, cmd.args),
            .Vinyl => try self.expectFloat(7, cmd.args),
            .RevDelay => try self.expectFloat(7, cmd.args),
            .Noise => try self.expectFloat(4, cmd.args),
            .WildNoise => try self.expectFloat(4, cmd.args),
            .Write => try self.expectFloat(3, cmd.args),
            .Rotate => try self.expectAny(2, cmd.args),
            .Embed => try self.expectAny(3, cmd.args),
            else => std.debug.warn("WARN unchecked command {}\n", .{cmd.command}),
        }
    }

    fn doError(self: *Lang, comptime fmt: []const u8, args: var) void {
        std.debug.warn("error at line {}: ", .{self.line});
        std.debug.warn(fmt, args);
        std.debug.warn("\n", .{});
        self.has_error = true;
    }

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

        while (splitted_it.next()) |stmt_orig| {
            self.line += 1;
            var stmt = std.mem.trimRight(u8, stmt_orig, "\n");
            stmt = std.mem.trimLeft(u8, stmt, "\n");

            if (stmt.len == 0) continue;
            if (std.mem.startsWith(u8, stmt, "#")) 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) {
                self.doError("No command given", .{});
                continue;
            }
            var command = cmd_opt.?;

            var ctype_opt = self.getCommand(command);
            var ctype: CommandType = undefined;
            if (ctype_opt) |ctype_val| {
                ctype = ctype_val;
            } else {
                self.doError("Unknown command '{}' ({})", .{ command, command.len });
                continue;
            }

            var args = ArgList.init(self.allocator);
            errdefer args.deinit();

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

            // construct final Command based on command
            var cmd = Command{ .command = ctype, .args = args };
            self.validateCommand(cmd) catch |err| {
                //self.doError("error validating command '{}': {}", command, err);
                continue;
            };

            try cmds.append(cmd);
        }

        if (self.has_error) return ParseError.ParseFail;

        return cmds;
    }
};

test "noop" {
    var lang = Lang.init(std.heap.direct_allocator);
    defer lang.deinit();

    var cmds = try lang.parse("noop;");
    defer cmds.deinit();

    std.testing.expectEqual(cmds.len, 1);
    std.testing.expectEqual(cmds.at(0).command, .Noop);
}

test "load, phaser, quicksave" {
    var lang = Lang.init(std.heap.direct_allocator);
    defer lang.deinit();

    const prog =
        \\load :0;
        \\phaser 3 1 25 0.25 0 1;
        \\quicksave;
    ;

    var cmds = try lang.parse(prog);
    defer cmds.deinit();

    std.testing.expectEqual(cmds.len, 3);
    std.testing.expectEqual(cmds.at(0).command, .Load);
    std.testing.expectEqual(cmds.at(1).command, .Phaser);
    std.testing.expectEqual(cmds.at(2).command, .Quicksave);
}