//! Canonicalization Data

nfc: std.AutoHashMapUnmanaged([2]u21, u21),
nfd: [][]u21 = undefined,

const CanonData = @This();

pub fn init(allocator: mem.Allocator) !CanonData {
    const decompressor = compress.flate.inflate.decompressor;
    const in_bytes = @embedFile("canon");
    var in_fbs = std.io.fixedBufferStream(in_bytes);
    var in_decomp = decompressor(.raw, in_fbs.reader());
    var reader = in_decomp.reader();

    const endian = builtin.cpu.arch.endian();
    var cdata = CanonData{
        .nfc = .empty,
        .nfd = try allocator.alloc([]u21, 0x110000),
    };
    var _cp: u24 = undefined;

    errdefer {
        cdata.nfc.deinit(allocator);
        for (cdata.nfd[0.._cp]) |slice| allocator.free(slice);
        allocator.free(cdata.nfd);
    }

    @memset(cdata.nfd, &.{});

    while (true) {
        const len: u8 = try reader.readInt(u8, endian);
        if (len == 0) break;
        const cp = try reader.readInt(u24, endian);
        _cp = cp;
        const nfd_cp = try allocator.alloc(u21, len - 1);
        errdefer allocator.free(nfd_cp);
        for (0..len - 1) |i| {
            nfd_cp[i] = @intCast(try reader.readInt(u24, endian));
        }
        if (len == 3) {
            try cdata.nfc.put(allocator, nfd_cp[0..2].*, @intCast(cp));
        }
        cdata.nfd[cp] = nfd_cp;
    }

    return cdata;
}

pub fn deinit(cdata: *CanonData, allocator: mem.Allocator) void {
    cdata.nfc.deinit(allocator);
    for (cdata.nfd) |slice| allocator.free(slice);
    allocator.free(cdata.nfd);
}

/// Returns canonical decomposition for `cp`.
pub fn toNfd(cdata: *const CanonData, cp: u21) []const u21 {
    return cdata.nfd[cp];
}

// Returns the primary composite for the codepoints in `cp`.
pub fn toNfc(cdata: *const CanonData, cps: [2]u21) ?u21 {
    return cdata.nfc.get(cps);
}

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