/// The data the API returns, as objects.
///
/// **Field names are the API's own, in Portuguese** — `logradouro`, `bairro`,
/// `localidade`. Everything else in this library is English; the fields are the
/// one deliberate exception.
///
/// The reason is fidelity: what you read in the JSON at
/// <https://cep.is/01001000> is exactly what you access on the object.
/// Translating to `street`/`city` would mean maintaining a field-by-field
/// mapping and forcing anyone reading the API docs alongside this library to
/// translate back in their head. The values are Portuguese either way — they
/// come from the Correios database.
///
/// Only the *casing* changes, where Dart demands it: the API's `raio_m` is
/// [Geo.raioM], its `cep_ini` and `cep_fim` are [Faixa.cepIni] and
/// [Faixa.cepFim], and its `base_gerada_em` is [Health.baseGeradaEm]. Every
/// other field is a single lowercase word and is spelled exactly as the API
/// spells it.
library;

/// The CEP's coordinate, when the database has one.
///
/// The point is the **median** of the coordinates of that CEP's addresses, not
/// the mean: one badly geocoded address 40 km away shifts a mean and does not
/// move a median.
///
/// Always check [precisao] — or the [isPrecise] shorthand — before using
/// [lat]/[lon] for distance:
///
/// - `'logradouro'`: the point is a stretch of street. [raioM] lands around
///   100–150 m. Good for maps and for distance.
/// - `'localidade'`: the CEP *is* the whole municipality (a city-wide general
///   CEP), and the point is its centroid. [raioM] runs from 7 km to 40 km.
///   Computing shipping from this is wrong by tens of kilometres.
class Geo {
  /// Creates a coordinate from its parts.
  const Geo({
    required this.lat,
    required this.lon,
    required this.raioM,
    required this.precisao,
  });

  /// Latitude in decimal degrees.
  final double lat;

  /// Longitude in decimal degrees.
  final double lon;

  /// Radius in metres containing 90% of that CEP's addresses.
  ///
  /// The API spells this field `raio_m`; Dart's naming rules make it `raioM`
  /// here. It exists precisely so the difference between a street-level point
  /// and a municipality centroid cannot pass unnoticed.
  final int raioM;

  /// Either `'logradouro'` (a stretch of street) or `'localidade'` (the
  /// municipality centroid). Treat any other value as imprecise.
  final String precisao;

  /// Builds a coordinate from the API's `geo` block, or returns `null`.
  ///
  /// A malformed block yields `null` rather than throwing: it is not worth
  /// losing the whole address over, since the rest of the response is still
  /// useful.
  static Geo? fromJson(Map<String, dynamic> data) {
    final lat = _toDouble(data['lat']);
    final lon = _toDouble(data['lon']);
    final raioM = _toInt(data['raio_m']);
    final precisao = data['precisao'];
    if (lat == null || lon == null || raioM == null || precisao == null) {
      return null;
    }
    return Geo(
      lat: lat,
      lon: lon,
      raioM: raioM,
      precisao: precisao is String ? precisao : precisao.toString(),
    );
  }

  /// `true` when the coordinate points at a street, not a municipality.
  ///
  /// Shorthand for `precisao == 'logradouro'`, which is the check to make
  /// before using the point to measure distance.
  bool get isPrecise => precisao == 'logradouro';

  @override
  bool operator ==(Object other) =>
      other is Geo &&
      other.lat == lat &&
      other.lon == lon &&
      other.raioM == raioM &&
      other.precisao == precisao;

  @override
  int get hashCode => Object.hash(lat, lon, raioM, precisao);

  @override
  String toString() =>
      'Geo(lat: $lat, lon: $lon, raioM: $raioM, precisao: $precisao)';
}

/// A CEP and everything the database knows about it.
///
/// Fields the database does not have for that CEP come back as empty strings,
/// never `null` — that is what the API returns, and changing it here would
/// create a difference between reading the JSON and reading this library.
///
/// [geo] is the exception: it is `null` when there is no coordinate. There the
/// difference is real, because the API **omits** the whole field in that case
/// (about 43% of CEPs) rather than sending null.
///
/// [raw] holds the response exactly as it arrived, uninterpreted, so a field
/// the API grows before this library is updated is not lost.
class Address {
  /// Creates an address from its parts. Every string field is required, so a
  /// missing value is an explicit `''` rather than an accident.
  const Address({
    required this.cep,
    required this.logradouro,
    required this.complemento,
    required this.unidade,
    required this.bairro,
    required this.localidade,
    required this.uf,
    required this.estado,
    required this.regiao,
    required this.ibge,
    required this.gia,
    required this.ddd,
    required this.siafi,
    this.geo,
    this.raw = const <String, dynamic>{},
  });

  /// The 8 digits, always unmasked. See [formattedCep] for `01001-000`.
  final String cep;

  /// Street, avenue or square.
  final String logradouro;

  /// Extra qualifier on the street, such as `'lado ímpar'`.
  final String complemento;

  /// Name of the large consumer or public body owning an exclusive CEP.
  final String unidade;

  /// Neighbourhood.
  final String bairro;

  /// Municipality.
  final String localidade;

  /// Two-letter state code, such as `'SP'`.
  final String uf;

  /// State name in full.
  final String estado;

  /// Region of the country, such as `'Sudeste'`.
  final String regiao;

  /// IBGE municipality code — the key to join against public census data.
  final String ibge;

  /// GIA code, São Paulo state tax administration only.
  final String gia;

  /// Area code for telephone numbers.
  final String ddd;

  /// SIAFI municipality code, federal government accounting.
  final String siafi;

  /// The coordinate, or `null` when the database has none for this CEP.
  ///
  /// Always `null` for an address that came out of a batch — see
  /// `Client.lookupMany`.
  final Geo? geo;

  /// The response exactly as it arrived, including fields this release does not
  /// model. Unmodifiable.
  final Map<String, dynamic> raw;

  /// Builds an address from the map the API returned.
  ///
  /// Unknown fields are ignored during construction but preserved in [raw]. A
  /// new field in the API therefore cannot break this library.
  ///
  /// A malformed `geo` block yields a `null` [geo] rather than propagating the
  /// error.
  factory Address.fromJson(Map<String, dynamic> data) {
    final block = data['geo'];
    return Address(
      cep: _text(data['cep']),
      logradouro: _text(data['logradouro']),
      complemento: _text(data['complemento']),
      unidade: _text(data['unidade']),
      bairro: _text(data['bairro']),
      localidade: _text(data['localidade']),
      uf: _text(data['uf']),
      estado: _text(data['estado']),
      regiao: _text(data['regiao']),
      ibge: _text(data['ibge']),
      gia: _text(data['gia']),
      ddd: _text(data['ddd']),
      siafi: _text(data['siafi']),
      geo: block is Map<String, dynamic> ? Geo.fromJson(block) : null,
      raw: Map<String, dynamic>.unmodifiable(data),
    );
  }

  /// The CEP with its mask: `01001-000`.
  ///
  /// The API always returns it unmasked; formatting is presentation, and it
  /// lives here so it does not become a repeated interpolation in every project
  /// that uses this.
  String get formattedCep =>
      cep.length == 8 ? '${cep.substring(0, 5)}-${cep.substring(5)}' : cep;

  /// Equality covers every modelled field, [geo] included. [raw] is excluded:
  /// two responses that differ only in a field this release does not model are
  /// the same address as far as this library is concerned.
  @override
  bool operator ==(Object other) =>
      other is Address &&
      other.cep == cep &&
      other.logradouro == logradouro &&
      other.complemento == complemento &&
      other.unidade == unidade &&
      other.bairro == bairro &&
      other.localidade == localidade &&
      other.uf == uf &&
      other.estado == estado &&
      other.regiao == regiao &&
      other.ibge == ibge &&
      other.gia == gia &&
      other.ddd == ddd &&
      other.siafi == siafi &&
      other.geo == geo;

  @override
  int get hashCode => Object.hash(
        cep,
        logradouro,
        complemento,
        unidade,
        bairro,
        localidade,
        uf,
        estado,
        regiao,
        ibge,
        gia,
        ddd,
        siafi,
        geo,
      );

  @override
  String toString() =>
      'Address(cep: $cep, logradouro: $logradouro, bairro: $bairro, '
      'localidade: $localidade, uf: $uf, geo: $geo)';
}

/// The municipality a CEP that does not exist *would* belong to.
///
/// This is what the API sends in the `faixa` block of a **404**, and it arrives
/// on `CepNotFoundException.faixa`. It is context for an error, never an
/// address: the CEP asked for still does not exist, and nothing here says
/// otherwise.
///
/// It exists because a failing CEP is rarely random — it is usually someone who
/// knows the city and guessed the number, and the classic guess is the `-000`,
/// which 957 municipalities never received. Naming the municipality turns "no"
/// into "no, but you were looking at Areal/RJ".
///
/// [cepIni] and [cepFim] are the smallest and the largest CEP that **actually
/// exist** in that municipality — not the bounds the Correios publish. Areal's
/// published range starts at `25845000`, which is exactly the CEP that just
/// failed; echoing it back would say nothing.
///
/// **The range is sparse.** Areal's [ceps] is 118, spread over the ~9000
/// numbers between [cepIni] and [cepFim]. The pair is not a list of valid CEPs
/// and iterating it would be wrong; [ceps] is there so the emptiness is
/// visible.
class Faixa {
  /// Creates a municipality band from its parts.
  const Faixa({
    required this.localidade,
    required this.uf,
    required this.estado,
    required this.regiao,
    required this.ibge,
    required this.cepIni,
    required this.cepFim,
    required this.ceps,
  });

  /// Municipality that owns the band the CEP fell in.
  final String localidade;

  /// Two-letter state code, such as `'RJ'`.
  final String uf;

  /// State name in full.
  final String estado;

  /// Region of the country, such as `'Sudeste'`.
  final String regiao;

  /// IBGE municipality code — the key to join against public census data.
  final String ibge;

  /// Smallest CEP that exists in the municipality, 8 digits.
  ///
  /// The API spells this field `cep_ini`; Dart's naming rules make it `cepIni`
  /// here. It is an observed minimum, not the Correios' published start.
  final String cepIni;

  /// Largest CEP that exists in the municipality, 8 digits.
  ///
  /// The API spells this field `cep_fim`; Dart's naming rules make it `cepFim`
  /// here. It is an observed maximum, not the Correios' published end.
  final String cepFim;

  /// How many CEPs exist between [cepIni] and [cepFim], inclusive.
  ///
  /// Almost always far fewer than the arithmetic distance between the two: the
  /// band is sparse, and this is the number that says how sparse.
  final int ceps;

  /// Builds a band from the API's `faixa` block, or returns `null`.
  ///
  /// A missing or malformed block yields `null` rather than throwing. The 404
  /// is the answer; losing it to a parse error over the hint attached to it
  /// would be a bad trade.
  ///
  /// `localidade` is the gate: without a municipality name there is nothing to
  /// tell the caller, so an empty one is the same as no block at all.
  static Faixa? fromJson(Map<String, dynamic> data) {
    final localidade = _text(data['localidade']);
    if (localidade.isEmpty) {
      return null;
    }
    return Faixa(
      localidade: localidade,
      uf: _text(data['uf']),
      estado: _text(data['estado']),
      regiao: _text(data['regiao']),
      ibge: _text(data['ibge']),
      cepIni: _text(data['cep_ini']),
      cepFim: _text(data['cep_fim']),
      ceps: _toInt(data['ceps']) ?? 0,
    );
  }

  @override
  bool operator ==(Object other) =>
      other is Faixa &&
      other.localidade == localidade &&
      other.uf == uf &&
      other.estado == estado &&
      other.regiao == regiao &&
      other.ibge == ibge &&
      other.cepIni == cepIni &&
      other.cepFim == cepFim &&
      other.ceps == ceps;

  @override
  int get hashCode => Object.hash(
        localidade,
        uf,
        estado,
        regiao,
        ibge,
        cepIni,
        cepFim,
        ceps,
      );

  @override
  String toString() =>
      'Faixa(localidade: $localidade, uf: $uf, cepIni: $cepIni, '
      'cepFim: $cepFim, ceps: $ceps)';
}

/// The response of `GET /health`.
///
/// Good for two things: checking that the API answers, and knowing **which
/// version of the database** is live. The DNE database changes every two weeks;
/// [dne] identifies it.
class Health {
  /// Creates a health report from its parts.
  const Health({
    required this.status,
    required this.dne,
    required this.ceps,
    required this.geo,
    required this.baseGeradaEm,
    this.raw = const <String, dynamic>{},
  });

  /// `'ok'` when the API considers itself healthy. See [ok].
  final String status;

  /// Identifier of the fortnightly DNE database currently loaded.
  final String dne;

  /// How many CEPs that database holds.
  final int ceps;

  /// How many of those CEPs carry a coordinate.
  final int geo;

  /// When the database was generated, as an ISO 8601 instant in UTC.
  ///
  /// The API spells this field `base_gerada_em`; Dart's naming rules make it
  /// `baseGeradaEm` here.
  final String baseGeradaEm;

  /// The response exactly as it arrived, including fields this release does not
  /// model. Unmodifiable.
  final Map<String, dynamic> raw;

  /// Builds a health report from the map the API returned.
  factory Health.fromJson(Map<String, dynamic> data) => Health(
        status: _text(data['status']),
        dne: _text(data['dne']),
        ceps: _toInt(data['ceps']) ?? 0,
        geo: _toInt(data['geo']) ?? 0,
        baseGeradaEm: _text(data['base_gerada_em']),
        raw: Map<String, dynamic>.unmodifiable(data),
      );

  /// `true` when the API reports itself healthy.
  bool get ok => status == 'ok';

  @override
  bool operator ==(Object other) =>
      other is Health &&
      other.status == status &&
      other.dne == dne &&
      other.ceps == ceps &&
      other.geo == geo &&
      other.baseGeradaEm == baseGeradaEm;

  @override
  int get hashCode => Object.hash(status, dne, ceps, geo, baseGeradaEm);

  @override
  String toString() =>
      'Health(status: $status, dne: $dne, ceps: $ceps, geo: $geo, '
      'baseGeradaEm: $baseGeradaEm)';
}

String _text(Object? value) {
  if (value == null) {
    return '';
  }
  return value is String ? value : value.toString();
}

double? _toDouble(Object? value) {
  if (value is num) {
    return value.toDouble();
  }
  if (value is String) {
    return double.tryParse(value);
  }
  return null;
}

int? _toInt(Object? value) {
  if (value is int) {
    return value;
  }
  if (value is num) {
    return value.toInt();
  }
  if (value is String) {
    return int.tryParse(value);
  }
  return null;
}