// JSON for packutils' requests, results and state files. The reader is strict: one document,
// duplicate members and bad escapes refused, numbers kept as their text. The writer prints
// Packwand's canonical form (2-space indent, `": "`, LF, a trailing newline, raw UTF-8, only `"`,
// `\` and control characters escaped), so a state file written here has the bytes Packwand's
// own writer gives. AI-authored (Claude).
#pragma once

#include <cstddef>
#include <cstdint>
#include <expected>
#include <optional>
#include <string>
#include <string_view>
#include <vector>

namespace packutils::json {

struct Member;

struct Value {
    enum class Type : std::uint8_t { null, boolean, number, string, array, object };

    Type type = Type::null;
    bool boolean = false;
    /// A number's text, or a string's decoded UTF-8.
    std::string text;
    std::vector<Value> items;
    /// In document order.
    std::vector<Member> members;

    [[nodiscard]] static Value of_string(std::string_view text);
    [[nodiscard]] static Value of_integer(std::int64_t number);
    [[nodiscard]] static Value of_bool(bool on);
    [[nodiscard]] static Value array();
    [[nodiscard]] static Value object();

    /// An object's member, or null.
    [[nodiscard]] const Value *get(std::string_view key) const;
    /// Appends a member to an object (the caller keeps keys unique).
    void put(std::string_view key, Value value);
    void push(Value value);

    [[nodiscard]] bool is(Type wanted) const { return type == wanted; }
    /// A string member's text, or nothing when it is missing or not a string.
    [[nodiscard]] std::optional<std::string_view> string_at(std::string_view key) const;
    /// A whole number in `[min, max]` (its text parsed exactly), or nothing.
    [[nodiscard]] std::optional<std::int64_t> integer(std::int64_t min, std::int64_t max) const;
};

struct Member {
    std::string key;
    Value value;
};

/// Why a document did not parse, with its byte offset.
struct ParseError {
    std::string message;
    std::size_t offset = 0;
};

[[nodiscard]] std::expected<Value, ParseError> parse(std::string_view bytes);

/// The canonical document with its trailing newline.
[[nodiscard]] std::string canonical(const Value &value);
/// One line, no spaces: for documents only a program reads.
[[nodiscard]] std::string compact(const Value &value);

} // namespace packutils::json