const std = @import("std");
const builtin = @import("builtin");
const compress = std.compress;
const mem = std.mem;

allocator: mem.Allocator,
s1: []u16 = undefined,
s2: []u8 = undefined,

const Self = @This();

pub fn init(allocator: mem.Allocator) !Self {
    const decompressor = compress.deflate.decompressor;
    const in_bytes = @embedFile("ccc");
    var in_fbs = std.io.fixedBufferStream(in_bytes);
    var in_decomp = try decompressor(allocator, in_fbs.reader(), null);
    defer in_decomp.deinit();
    var reader = in_decomp.reader();

    const endian = builtin.cpu.arch.endian();

    var self = Self{ .allocator = allocator };

    const stage_1_len: u16 = try reader.readInt(u16, endian);
    self.s1 = try allocator.alloc(u16, stage_1_len);
    for (0..stage_1_len) |i| self.s1[i] = try reader.readInt(u16, endian);

    const stage_2_len: u16 = try reader.readInt(u16, endian);
    self.s2 = try allocator.alloc(u8, stage_2_len);
    _ = try reader.readAll(self.s2);

    return self;
}

pub fn deinit(self: *Self) void {
    self.allocator.free(self.s1);
    self.allocator.free(self.s2);
}

/// Returns the canonical combining class for a code point.
pub inline fn ccc(self: Self, cp: u21) u8 {
    return self.s2[self.s1[cp >> 8] + (cp & 0xff)];
}

/// True if `cp` is a starter code point, not a combining character.
pub inline fn isStarter(self: Self, cp: u21) bool {
    return self.s2[self.s1[cp >> 8] + (cp & 0xff)] == 0;
}