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,
    Saturator,
    VintageDelay,

    Noise,
    WildNoise,
    Write,
    Embed,

    Rotate,
};

pub const Type = enum {
    /// "LV2 Commands" are commands that receive split, index, and then receive
    /// any f64 arguments.
    lv2_command,
};

pub const NewCommand = struct {
    tag: Tag,

    pub const Tag = 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,
        saturator,
        vintagedelay,

        noise,
        wildnoise,
        write,
        embed,

        rotate,
    };

    pub fn cast(base: *@This(), comptime T: type) ?*T {
        if (base.tag != T.base_tag)
            return null;

        return @fieldParentPtr(T, "base", base);
    }

    pub const Noop = struct {
        pub const base_tag = Tag.noop;
        base: NewCommand,
    };

    pub const Load = struct {
        pub const base_tag = Tag.load;
        base: NewCommand,
        path: []const u8,
    };

    pub const Quicksave = struct {
        pub const base_tag = Tag.quicksave;
        base: NewCommand,
    };

    pub const RunQS = struct {
        pub const base_tag = Tag.runqs;
        program: []const u8,
        base: NewCommand,
    };

    pub const Amp = struct {
        pub const base_tag = Tag.amp;
        pub const base_type = Type.lv2_command;
        base: NewCommand,
        gain: f64
    };

    pub const RFlanger = struct {
        pub const base_tag = Tag.rflanger;
        pub const base_type = Type.lv2_command;
        base: NewCommand,
        delay_depth_avg: f64,
        law_freq: f64,
    };
};

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.items.len });

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

        return self.args.items[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.items;
    }

    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(NewCommand);
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 {
        inline for (@typeInfo(NewCommand).Struct.decls) |cmd_struct_decl| {
            switch (cmd_struct_decl.data) {
                .Type => |typ| switch (@typeInfo(typ)) {
                    .Struct => {},
                    else => continue,
                },
                else => continue,
            }

            const struct_name = cmd_struct_decl.name;

            comptime var lowered_command_name = [_]u8{0} ** struct_name.len;
            comptime {
                for (struct_name) |c, i| {
                    lowered_command_name[i] = std.ascii.toLower(c);
                }
            }

            _ = try self.keywords.put(&lowered_command_name, @field(CommandType, struct_name));
        }
    }

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

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

    fn parseCommandArguments(
        self: *@This(),
        comptime command_struct: type,
        tok_it: *std.mem.TokenIterator,
        commands: *CommandList,
    ) !void {
        // Based on the command struct fields, we can parse the arguments.
        var cmd = try self.allocator.create(command_struct);

        inline for (@typeInfo(command_struct).Struct.fields) |cmd_field| {
            comptime {
                if (std.mem.eql(u8, cmd_field.name, "base")) {
                    continue;
                }
            }

            // TODO: crash when no arguments are left but we still need
            // arguments...
            const arg = tok_it.next().?;
            const argument_value = switch (cmd_field.field_type) {
                usize => try std.fmt.parseInt(usize, arg, 10),
                i32 => try std.fmt.parseInt(i32, arg, 10),
                f32 => try std.fmt.parseFloat(f32, arg),
                []const u8 => arg,
                else => @panic("Invalid parameter type (" ++ @typeName(cmd_field.field_type) ++ ") left on command struct " ++ @typeName(command_struct) ++ "."),
            };

            @field(cmd, cmd_field.name) = argument_value;
        }

        try commands.append(cmd.base);
    }

    pub fn parse(self: *Lang, data: []const u8) ParseError!CommandList {
        var splitted_it = std.mem.split(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(" ")...maybe????
            var tok_it = std.mem.tokenize(stmt, " ");

            var cmd_opt = tok_it.next();
            if (cmd_opt == null) {
                self.doError("No command given", .{});
                continue;
            }
            const command_string = cmd_opt.?;

            var found: bool = false;

            inline for (@typeInfo(NewCommand).Struct.decls) |cmd_struct_decl| {
                switch (cmd_struct_decl.data) {
                    .Type => |typ| switch (@typeInfo(typ)) {
                        .Struct => {},
                        else => continue,
                    },
                    else => continue,
                }

                const struct_name = cmd_struct_decl.name;
                comptime var lowered_command_name = [_]u8{0} ** struct_name.len;
                comptime {
                    for (struct_name) |c, i| {
                        lowered_command_name[i] = std.ascii.toLower(c);
                    }
                }

                // if we have a match, we know the proper struct type
                // to use. this actually works compared to storing command_struct
                // in a variable because then that variable must be comptime.

                // the drawback of this approach is that our emitted code is basically linear
                // because we don't use the hashmap anymore. maybe #5359 can help.

                if (std.mem.eql(u8, &lowered_command_name, command_string)) {
                    found = true;
                    const cmd_struct_type = cmd_struct_decl.data.Type;
                    try self.parseCommandArguments(cmd_struct_type, &tok_it, &cmds);
                }
            }

            if (!found) {
                self.doError("Unknown command '{}' ({})", .{ command_string, command_string.len });
                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.items[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.items[0].command, .Load);
    std.testing.expectEqual(cmds.items[1].command, .Phaser);
    std.testing.expectEqual(cmds.items[2].command, .Quicksave);
}