import 'dart:async';

import 'package:inventree/api.dart';
import 'package:flutter/cupertino.dart';
import 'package:url_launcher/url_launcher.dart';

import 'package:path/path.dart' as path;


// Paginated response object
class InvenTreePageResponse {

  InvenTreePageResponse() {
    results = [];
  }

  void addResult(InvenTreeModel item) {
    results.add(item);
  }

  // Total number of results in the dataset
  int count = 0;
  
  int get length => results.length;

  List<InvenTreeModel> results = [];
}

/**
 * The InvenTreeModel class provides a base-level object
 * for interacting with InvenTree data.
 */
class InvenTreeModel {

  // Override the endpoint URL for each subclass
  String URL = "";

  // Override the web URL for each subclass
  // Note: If the WEB_URL is the same (except for /api/) as URL then just leave blank
  String WEB_URL = "";

  String NAME = "Model";

  String get webUrl {

    if (api.isConnected()) {
      String web = InvenTreeAPI().baseUrl;

      web += WEB_URL.isNotEmpty ? WEB_URL : URL;

      web += "/${pk}/";

      web = web.replaceAll("//", "/");

      return web;

    } else {
      return "";
    }

  }

  // JSON data which defines this object
  Map<String, dynamic> jsondata = {};

  // Accessor for the API
  var api = InvenTreeAPI();

  // Default empty object constructor
  InvenTreeModel() {
    jsondata.clear();
  }

  // Construct an InvenTreeModel from a JSON data object
  InvenTreeModel.fromJson(Map<String, dynamic> json) {

    // Store the json object
    jsondata = json;

  }

  int get pk => (jsondata['pk'] ?? -1) as int;

  // Some common accessors
  String get name => jsondata['name'] ?? '';

  String get description => jsondata['description'] ?? '';

  String get notes => jsondata['notes'] ?? '';

  int get parentId => (jsondata['parent'] ?? -1) as int;

  // Legacy API provided external link as "URL", while newer API uses "link"
  String get link => jsondata['link'] ?? jsondata['URL'] ?? '';

  void goToInvenTreePage() async {

    if (await canLaunch(webUrl)) {
      await launch(webUrl);
    } else {
      // TODO
    }
  }

  void openLink() async {

    if (link.isNotEmpty) {
      print("Opening link: ${link}");

      if (await canLaunch(link)) {
        await launch(link);
      } else {
        // TODO
      }
    }
  }

  String get keywords => jsondata['keywords'] ?? '';

  // Create a new object from JSON data (not a constructor!)
  InvenTreeModel createFromJson(Map<String, dynamic> json) {

      var obj = InvenTreeModel.fromJson(json);

      return obj;
  }

  // Return the API detail endpoint for this Model object
  String get url => "${URL}/${pk}/".replaceAll("//", "/");

  // Search this Model type in the database
  Future<List<InvenTreeModel>> search(BuildContext context, String searchTerm, {Map<String, String> filters = const {}}) async {

    filters["search"] = searchTerm;

    final results = list(filters: filters);

    return results;

  }

  Map<String, String> defaultListFilters() { return Map<String, String>(); }

  // A map of "default" headers to use when performing a GET request
  Map<String, String> defaultGetFilters() { return Map<String, String>(); }

  /*
   * Reload this object, by requesting data from the server
   */
  Future<bool> reload() async {

    var response = await api.get(url, params: defaultGetFilters(), expectedStatusCode: 200);
    
    if (!response.isValid()) {
      return false;
    }

    jsondata = response.data;

    return true;
  }

  // POST data to update the model
  Future<bool> update({Map<String, String> values = const {}}) async {

    var url = path.join(URL, pk.toString());

    if (!url.endsWith("/")) {
      url += "/";
    }

    var response = await api.patch(
      url,
      body: values,
      expectedStatusCode: 200
    );

    if (!response.isValid()) {
      return false;
    }

    return true;
  }

  // Return the detail view for the associated pk
  Future<InvenTreeModel?> get(int pk, {Map<String, String> filters = const {}}) async {

    // TODO - Add "timeout"
    // TODO - Add error catching

    var url = path.join(URL, pk.toString());

    if (!url.endsWith("/")) {
      url += "/";
    }

    var params = defaultGetFilters();

    // Override any default values
    for (String key in filters.keys) {
      params[key] = filters[key] ?? '';
    }

    var response = await api.get(url, params: params);

    if (!response.isValid()) {
      return null;
    }

    return createFromJson(response.data);
  }

  Future<InvenTreeModel?> create(Map<String, dynamic> data) async {

    print("CREATE: ${URL} ${data.toString()}");

    if (data.containsKey('pk')) {
      data.remove('pk');
    }

    if (data.containsKey('id')) {
      data.remove('id');
    }

    var response = await api.post(URL, body: data);

    // Invalid response returned from server
    if (!response.isValid()) {
      return null;
    }

    return createFromJson(response.data);
  }

  Future<InvenTreePageResponse?> listPaginated(int limit, int offset, {Map<String, String> filters = const {}}) async {
    var params = defaultListFilters();

    for (String key in filters.keys) {
      params[key] = filters[key] ?? '';
    }

    params["limit"] = "${limit}";
    params["offset"] = "${offset}";

    var response = await api.get(URL, params: params);

    if (!response.isValid()) {
      return null;
    }

    // Construct the response
    InvenTreePageResponse page = new InvenTreePageResponse();

    if (response.data.containsKey("count") && response.data.containsKey("results")) {
       page.count = response.data["count"] as int;

       page.results = [];

       for (var result in response.data["results"]) {
         page.addResult(createFromJson(result));
       }

       return page;

    } else {
      return null;
    }
  }

  // Return list of objects from the database, with optional filters
  Future<List<InvenTreeModel>> list({Map<String, String> filters = const {}}) async {

    var params = defaultListFilters();

    for (String key in filters.keys) {
      params[key] = filters[key] ?? '';
    }

    var response = await api.get(URL, params: params);

    // A list of "InvenTreeModel" items
    List<InvenTreeModel> results = [];

    if (!response.isValid()) {
      return results;
    }

    // TODO - handle possible error cases:
    // - No data receieved
    // - Data is not a list of maps

    for (var d in response.data) {

      // Create a new object (of the current class type
      InvenTreeModel obj = createFromJson(d);

      results.add(obj);
    }

    return results;
  }


  // Provide a listing of objects at the endpoint
  // TODO - Static function which returns a list of objects (of this class)

  // TODO - Define a 'delete' function

  // TODO - Define a 'save' / 'update' function

  // Override this function for each sub-class
  bool matchAgainstString(String filter) {
    // Default implementation matches name and description
    // Override this behaviour in sub-class if required

    if (name.toLowerCase().contains(filter)) return true;
    if (description.toLowerCase().contains(filter)) return true;

    // No matches!
    return false;
  }

  // Filter this item against a list of provided filters
  // Each filter must be matched
  // Used for (e.g.) filtering returned results
  bool filter(String filterString) {

    List<String> filters = filterString.trim().toLowerCase().split(" ");

    for (var f in filters) {
      if (!matchAgainstString(f)) {
        return false;
      }
    }

    return true;
  }
}