// Official spec defined code points.
// See https://infra.spec.whatwg.org/#code-points for spec.

import { writeFileSync } from "fs";
import { RUST_OUT_DIR } from "./_common";
import { join } from "path";

const rangeInclusive = (from: number, to: number) =>
  Array.from({ length: to - from + 1 }, (_, i) => from + i);
const invert = (codepoints: number[]) =>
  Array.from({ length: 256 }, (_, i) =>
    codepoints.includes(i) ? undefined : i
  ).filter((c) => c != undefined);
const c = (char: string) => char.charCodeAt(0);

// Also update gen/tries.json when changing whitespace definition.
const WHITESPACE = [0x09, 0x0a, 0x0c, 0x0d, 0x20];
const C0_CONTROL = rangeInclusive(0, 0x1f);
const CONTROL = [...C0_CONTROL, ...rangeInclusive(0x7f, 0x9f)];
const DIGIT = rangeInclusive(c("0"), c("9"));
const UPPER_HEX_ALPHA = [...rangeInclusive(c("A"), c("F"))];
const LOWER_HEX_ALPHA = [...rangeInclusive(c("a"), c("f"))];
const HEX_DIGIT = [...DIGIT, ...UPPER_HEX_ALPHA, ...LOWER_HEX_ALPHA];
const UPPER_ALPHA = rangeInclusive(c("A"), c("Z"));
const LOWER_ALPHA = rangeInclusive(c("a"), c("z"));
const ALPHA = [...UPPER_ALPHA, ...LOWER_ALPHA];
const ALPHANUMERIC = [...DIGIT, ...ALPHA];
const ALPHANUMERIC_OR_EQUALS = [...DIGIT, ...ALPHA, c("=")];

// Browsers are much more lax than the spec with regards to attribute names.
// See https://html.spec.whatwg.org/multipage/syntax.html#syntax-attribute-name for spec.
// To understand browser behaviour, try parsing:
/*
<input type


       =
    "password"  "a"  = "b"   :cd  /e /=fg 	= /\h /i/ /j/k/l m=n=o q==\r/s/ / t] = /u  / w=//>
 */
const WHITESPACE_OR_SLASH = [...WHITESPACE, c("/")];
const WHITESPACE_OR_SLASH_OR_EQUALS = [...WHITESPACE_OR_SLASH, c("=")];
const WHITESPACE_OR_SLASH_OR_EQUALS_OR_RIGHT_CHEVRON = [
  ...WHITESPACE_OR_SLASH_OR_EQUALS,
  c(">"),
];

const DOUBLE_QUOTE = [c('"')];
const SINGLE_QUOTE = [c("'")];
// Official characters allowed in an attribute name.
// NOTE: Unicode noncharacters not tested.
// See https://html.spec.whatwg.org/multipage/syntax.html#syntax-attribute-name for spec.
const WHATWG_ATTR_NAME_CHAR = invert([
  ...CONTROL,
  c(" "),
  c('"'),
  c("'"),
  c(">"),
  c("/"),
  c("="),
]);
// Valid attribute quote characters.
// See https://html.spec.whatwg.org/multipage/introduction.html#intro-early-example for spec.
// Backtick is not a valid quote character according to spec.
const ATTR_QUOTE = [...DOUBLE_QUOTE, ...SINGLE_QUOTE];
// Valid unquoted attribute value characters.
// See https://html.spec.whatwg.org/multipage/syntax.html#unquoted for spec.
// Browsers seem to simply consider any characters until whitespace or `>` part of an unquoted attribute value, despite the spec having more restrictions on allowed characters.
const NOT_UNQUOTED_ATTR_VAL_CHAR = [...WHITESPACE, c(">")];

// Tag names may only use ASCII alphanumerics. However, some people also use `:` and `-`.
// See https://html.spec.whatwg.org/multipage/syntax.html#syntax-tag-name for spec.
const TAG_NAME_CHAR = [...ALPHANUMERIC, c(":"), c("-")];

const output =
  `
pub struct Lookup {
  table: [bool; 256],
}

impl std::ops::Index<u8> for Lookup {
  type Output = bool;
  
  fn index(&self, c: u8) -> &Self::Output {
    // \`c\` is definitely below 256 so it's always safe to directly index table without checking.
    unsafe {
      self.table.get_unchecked(c as usize)
    } 
  }
}

` +
  Object.entries({
    WHITESPACE,
    DIGIT,
    UPPER_HEX_ALPHA,
    LOWER_HEX_ALPHA,
    HEX_DIGIT,
    ALPHANUMERIC_OR_EQUALS,

    WHITESPACE_OR_SLASH,
    WHITESPACE_OR_SLASH_OR_EQUALS_OR_RIGHT_CHEVRON,

    WHATWG_ATTR_NAME_CHAR,
    DOUBLE_QUOTE,
    SINGLE_QUOTE,
    ATTR_QUOTE,
    NOT_UNQUOTED_ATTR_VAL_CHAR,

    TAG_NAME_CHAR,
  })
    .map(
      ([name, points]) => `
pub static ${name}: &Lookup = &Lookup {
  table: [${Array.from({ length: 256 }, (_, i) => points.includes(i)).join(
    ", "
  )}],
};`
    )
    .join("\n\n");

writeFileSync(join(RUST_OUT_DIR, "codepoints.rs"), output);