// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®

export module Crafter.Review:Text;
import std;
import :Json;

// The text, number, URL and path semantics every other partition relies on.
// Where a result reaches a prompt, a reuse key, a shared file or an exit code
// it is decided by these exact rules — Unicode whitespace in Strip(), U+2028
// in SplitLines(), code points in Length(), half-even Round(), FnMatch()'s
// character classes — never by the nearest C++ equivalent. tests/Text checks
// every function against the reference vectors in tests/Text/fixture.
//
// Text is UTF-8 in std::string. Lengths and indices are in code points.
//
// Lower() maps Greek capital sigma to σ everywhere: it never writes the
// final form ς.
export namespace Crafter::Review::Dyn {
    // ---- UTF-8 -------------------------------------------------------------
    // Each maximal subpart of an ill-formed sequence becomes one U+FFFD, the
    // Unicode Standard's recommended practice.
    std::u32string Decode(std::string_view utf8);
    std::string Encode(std::u32string_view text);
    std::string Encode(char32_t c);
    // Well-formed UTF-8: no overlong forms, no surrogates, nothing above
    // U+10FFFF.
    bool IsUtf8(std::string_view bytes);
    // bytes.decode('utf-8', 'replace').
    std::string DecodeReplace(std::string_view bytes);
    // len()
    std::size_t Length(std::string_view text);
    // The code points from start to end: a negative index counts from the
    // end, and both are clipped to the text.
    std::string Slice(std::string_view text, std::int64_t start, std::optional<std::int64_t> end = std::nullopt);
    // The code point at byte `at` and the bytes it takes: U+FFFD and the
    // length of the invalid sequence where the bytes are no UTF-8.
    std::pair<char32_t, std::size_t> CodePointAt(std::string_view text, std::size_t at);
    // [start, end) of a slice of `size` items: a negative index counts from
    // the end, and both are clipped to the sequence.
    std::pair<std::size_t, std::size_t> SliceBounds(std::size_t size, std::int64_t start, std::optional<std::int64_t> end = std::nullopt);

    // ---- regex classes, for the hand-written scanners -----------------------
    // The bytes of the run at `at` of regex \d (Unicode decimal digits), \s
    // (Unicode whitespace) or \S characters.
    std::size_t DecimalRun(std::string_view text, std::size_t at);
    std::size_t SpaceRun(std::string_view text, std::size_t at);
    std::size_t NonSpaceRun(std::string_view text, std::size_t at);

    // ---- characters ----------------------------------------------------------
    bool IsSpace(char32_t c);
    bool IsLineBreak(char32_t c);
    bool IsDecimal(char32_t c);
    // The digit's value, -1 for a character that is not a decimal digit.
    std::int32_t DecimalValue(char32_t c);
    bool IsPrintable(char32_t c);
    // regex \w: what \b takes for a word character.
    bool IsWord(char32_t c);
    // The lowercase ASCII letter `c` matches case-insensitively, or '\0':
    // ASCII letters, and the four code points outside ASCII that fold onto
    // one (İ ı → i, ſ → s, K → k).
    char IgnoreCaseLetter(char32_t c);

    // ---- str methods ----------------------------------------------------------
    // strip()/lstrip()/rstrip(): Unicode whitespace.
    std::string Strip(std::string_view text);
    std::string LStrip(std::string_view text);
    std::string RStrip(std::string_view text);
    // strip(chars): the code points of `chars`.
    std::string Strip(std::string_view text, std::string_view chars);
    std::string LStrip(std::string_view text, std::string_view chars);
    std::string RStrip(std::string_view text, std::string_view chars);
    // split(): runs of Unicode whitespace, no empty pieces.
    std::vector<std::string> Split(std::string_view text);
    // split(sep, maxsplit) / rsplit(sep, maxsplit): every piece, empty ones
    // included; a negative maxSplit splits at every separator.
    std::vector<std::string> Split(std::string_view text, std::string_view separator, std::int64_t maxSplit = -1);
    std::vector<std::string> RSplit(std::string_view text, std::string_view separator, std::int64_t maxSplit = -1);
    // splitlines(keepends): \n, \r, \r\n, \v, \f, \x1c-\x1e, \x85, U+2028,
    // U+2029; no empty piece after a final line break.
    std::vector<std::string> SplitLines(std::string_view text, bool keepEnds = false);
    std::string Lower(std::string_view text);
    std::string Upper(std::string_view text);
    // count(sub): non-overlapping; an empty `sub` counts len() + 1.
    std::size_t Count(std::string_view text, std::string_view sub);
    std::string Replace(std::string_view text, std::string_view from, std::string_view to);
    std::string Join(std::span<const std::string> parts, std::string_view separator);
    // f'{text:<width}' / text.ljust(width): padded with spaces to `width`
    // code points, where std::format would count display columns.
    std::string LJust(std::string_view text, std::size_t width);

    // ---- reading text files ----------------------------------------------------
    // A text file, read whole: strict UTF-8 — invalid bytes throw Error
    // ("UnicodeDecodeError") with Utf8DecodeError()'s message — and universal
    // newlines. A file that cannot be opened throws Error ("FileNotFoundError").
    std::string ReadText(const std::filesystem::path& path);
    // \r\n and a lone \r become \n, as text mode reads them.
    std::string UniversalNewlines(std::string_view text);
    // The message for bytes that are not UTF-8 — "'utf-8' codec can't decode
    // byte 0xff in position 3: invalid start byte" — nullopt for valid UTF-8.
    std::optional<std::string> Utf8DecodeError(std::string_view bytes);
    // The message for text that is no JSON document, with the scanner's
    // reason and position ("Expecting ',' delimiter: line 3 column 5 (char
    // 21)"); nullopt for a document LoadJsonFile() takes.
    std::optional<std::string> JsonDecodeError(std::string_view text);
    // A JSON file: read as text, then parsed. Throws Error with the message a
    // "not JSON (...)" problem carries: the decode error, or the JSON error.
    Json LoadJsonFile(const std::filesystem::path& path);

    // ---- numbers ------------------------------------------------------------------
    // A float as its shortest digits that round-trip; an exponent below 1e-4
    // and from 1e16 up; ".0" on an integral value; inf, nan.
    std::string FloatRepr(double value);
    // value to `digits` decimals: correctly rounded, half to even on exact
    // ties.
    double Round(double value, std::int32_t digits);
    // value to the nearest integer, half to even.
    std::int64_t RoundToInt(double value);
    // An integer or a float from text: surrounding Unicode whitespace ignored,
    // Unicode decimal digits accepted, single underscores between digits
    // allowed. nullopt for anything else (and, for an integer, beyond 64 bits).
    std::optional<std::int64_t> ParseInt(std::string_view text);
    std::optional<double> ParseFloat(std::string_view text);
    // The ValueError messages for those.
    std::string IntError(std::string_view text);
    std::string FloatError(std::string_view text);

    // ---- repr ----------------------------------------------------------------------
    std::string Repr(std::string_view text);
    // A JSON value printed for a message: objects as {'key': value}, strings
    // quoted, true, false and null as True, False and None.
    std::string ReprValue(const Json& value);

    // ---- shell patterns ---------------------------------------------------------------
    // A shell-style pattern: case-sensitive, `*` crosses `/`, `[!...]` negates,
    // an unclosed `[` is literal and a reversed range matches nothing.
    bool FnMatch(std::string_view name, std::string_view pattern);

    // ---- URLs ---------------------------------------------------------------------------
    struct SplitUrl {
        std::string scheme;
        std::string netloc;
        std::string path;
        std::string query;
        std::string fragment;
        // .hostname: lowercased, nullopt when there is none.
        std::optional<std::string> Hostname() const;
        std::optional<std::string> Username() const;
        std::optional<std::string> Password() const;
        // .port: nullopt for none; std::invalid_argument with a ValueError
        // message for one that is not a number or out of range.
        std::optional<std::int32_t> Port() const;
    };
    // A URL's scheme, netloc, path, query and fragment. Throws
    // std::invalid_argument with a ValueError message for unbalanced or
    // invalid brackets.
    SplitUrl UrlSplit(std::string_view url);
    // The five parts joined back into a URL: an empty query or fragment gets
    // no '?' or '#'.
    std::string UrlUnsplit(std::string_view scheme, std::string_view netloc, std::string_view path, std::string_view query, std::string_view fragment);
    // unquote(text): %XX sequences decoded as UTF-8, bad bytes replaced.
    std::string Unquote(std::string_view text);

    // ---- natural sort ---------------------------------------------------------------------
    // A name cut into digit runs and the text between them, compared element
    // by element, a digit run by its value.
    struct NaturalKey {
        std::vector<std::variant<std::string, std::int64_t>> parts;
        std::strong_ordering operator<=>(const NaturalKey& other) const = default;
        bool operator==(const NaturalKey& other) const = default;
    };
    NaturalKey Natural(std::string_view name);

    // ---- POSIX paths -----------------------------------------------------------------------
    std::string NormPath(std::string_view path);
    // Against the current directory, lexically: symlinks are not resolved.
    std::string AbsPath(std::string_view path);
    std::string RelPath(std::string_view path, std::string_view start = ".");
    std::string BaseName(std::string_view path);
    std::string DirName(std::string_view path);
    std::string JoinPath(std::string_view a, std::string_view b);

    // ---- errno texts -------------------------------------------------------------------------
    // "[Errno 111] Connection refused": an errno as a message prints it.
    std::string ErrnoText(std::int32_t code);

    // ---- exceptions ------------------------------------------------------------------------------
    // Data the code does not expect — a key that is absent, a value of the
    // wrong type, a lookup in something that is no object — throws Error
    // named for the case (KeyError, TypeError, AttributeError): a caller
    // catches the names it expects, and anything else fails loudly.
    class Error : public std::runtime_error {
    public:
        Error(std::string_view kind, const std::string& message);
        const std::string& Kind() const;

    private:
        std::string kind;
    };

    // ---- JSON values ---------------------------------------------------------------------------------
    // The driver's data — units, jobs, results, dispositions, the config, the
    // claude stream — stays JSON from end to end, so every key keeps its place
    // and its unknown neighbours. These are the operations on it.
    //
    // Truthiness: null, false, 0, 0.0, "", [] and {} are false.
    bool Truthy(const Json& value);
    // `value or fallback`. A reference to one of the two, so neither may be a
    // temporary: name the fallback, or use EmptyDict()/EmptyList().
    const Json& Or(const Json& value, const Json& fallback);
    const Json& Or(Json&& value, const Json& fallback) = delete;
    const Json& Or(const Json& value, Json&& fallback) = delete;
    // The shared {} and [] that `x or {}` and `x or []` fall back to.
    const Json& EmptyDict();
    const Json& EmptyList();
    // Whether an object has the key; false for anything that is no object.
    bool Has(const Json& dict, std::string_view key);
    // The key's value, null when it is absent; Error (AttributeError) on
    // something that is no object.
    const Json& Get(const Json& dict, std::string_view key);
    // The key's value; Error (KeyError) when it is absent.
    const Json& At(const Json& dict, std::string_view key);
    // The type name messages use: dict, list, str, int, float, bool, NoneType.
    std::string_view TypeName(const Json& value);
    // An integer, a bool included.
    bool IsInt(const Json& value);
    // An integer or a float, a bool included.
    bool IsNumber(const Json& value);
    // A string as it is, anything else as ReprValue() prints it.
    std::string Str(const Json& value);
    // Str() of the value, or of the fallback when the value is falsy.
    std::string StrOr(const Json& value, std::string_view fallback);
    // a == b: numbers by value (True == 1 == 1.0), dicts whatever their key
    // order, a str never equal to a number.
    bool Equal(const Json& a, const Json& b);
    // Membership: an element of a list, a key of an object, a substring of a
    // string (Error when the item is no string there).
    bool In(const Json& item, const Json& container);
    // a + b on numbers: int + int stays an int, a float makes a float, a bool
    // counts as 0 or 1; Error (TypeError) for anything else.
    Json Add(const Json& a, const Json& b);
    // A total of floats by Neumaier's compensated summation, so it comes out
    // to the same last bit as the goldens record it.
    double Sum(std::span<const double> values);
}