import "package:flutter/services.dart";
import "package:flutter_test/flutter_test.dart";
import "package:garage_ui/garage_ui.dart";

/// Type [text] one character at a time through [f], the way a keyboard would.
///
/// Feeding the whole string in one go would only ever test paste - and a mask
/// that handles paste can still put the caret in the wrong place on every
/// keystroke, which is the bug people actually hit.
TextEditingValue _type(MaskedTextInputFormatter f, String text) {
  var v = TextEditingValue.empty;
  for (final ch in text.split("")) {
    final at = v.selection.baseOffset < 0
        ? v.text.length
        : v.selection.baseOffset;
    final next = TextEditingValue(
      text: v.text.substring(0, at) + ch + v.text.substring(at),
      selection: TextSelection.collapsed(offset: at + 1),
    );
    v = f.formatEditUpdate(v, next);
  }
  return v;
}

/// One backspace at the caret.
TextEditingValue _backspace(MaskedTextInputFormatter f, TextEditingValue v) {
  final at = v.selection.baseOffset;
  if (at <= 0) return v;
  return f.formatEditUpdate(
    v,
    TextEditingValue(
      text: v.text.substring(0, at - 1) + v.text.substring(at),
      selection: TextSelection.collapsed(offset: at - 1),
    ),
  );
}

TextEditingValue _paste(MaskedTextInputFormatter f, String text) =>
    f.formatEditUpdate(
      TextEditingValue.empty,
      TextEditingValue(
        text: text,
        selection: TextSelection.collapsed(offset: text.length),
      ),
    );

void main() {
  final phone = MaskedTextInputFormatter("### ###-####");

  group("typing", () {
    test("literals arrive on their own", () {
      expect(_type(phone, "5").text, "5");
      expect(_type(phone, "555").text, "555");
      // the space appears with the 4th digit, not before it - a trailing
      // literal you cant delete reads as the field being stuck
      expect(_type(phone, "5551").text, "555 1");
      expect(_type(phone, "555123").text, "555 123");
      expect(_type(phone, "5551234").text, "555 123-4");
      expect(_type(phone, "5551234567").text, "555 123-4567");
    });

    test("the caret stays after what you typed", () {
      final v = _type(phone, "5551");
      expect(v.text, "555 1");
      expect(v.selection.baseOffset, 5);
    });

    test("it stops when the mask is full", () {
      expect(_type(phone, "55512345678901").text, "555 123-4567");
    });

    test("characters the slot wont take are dropped, not the whole edit", () {
      expect(_type(phone, "5a5b5c").text, "555");
    });
  });

  group("deleting", () {
    test("backspace over a literal still removes a character", () {
      // the case a naive mask gets stuck on: the caret is just past the space,
      // backspace kills the space, the digits are unchanged, and re-applying
      // the mask puts the space straight back.
      var v = _type(phone, "5551");
      expect(v.text, "555 1");
      v = _backspace(phone, v);
      expect(v.text, "555");
      v = _backspace(phone, v);
      expect(v.text, "55");
    });

    test("backspacing the lot empties the field", () {
      var v = _type(phone, "5551234567");
      for (var i = 0; i < 20; i++) {
        v = _backspace(phone, v);
      }
      expect(v.text, "");
    });

    test("backspace at the start is a no-op, not a crash", () {
      final v = phone.formatEditUpdate(
        TextEditingValue.empty,
        TextEditingValue.empty,
      );
      expect(v.text, "");
      expect(_backspace(phone, v).text, "");
    });
  });

  group("pasting", () {
    test("an already formatted number survives", () {
      expect(_paste(phone, "555 123-4567").text, "555 123-4567");
    });

    test("someone elses formatting is reduced and re-laid", () {
      expect(_paste(phone, "(555) 123-4567").text, "555 123-4567");
      expect(_paste(phone, "555.123.4567").text, "555 123-4567");
      expect(_paste(phone, "5551234567").text, "555 123-4567");
    });

    test("overlong paste is cut to the mask", () {
      expect(_paste(phone, "555123456789").text, "555 123-4567");
    });
  });

  group("slot kinds", () {
    test("A takes letters, # takes digits", () {
      final post = MaskedTextInputFormatter("AA# #AA");
      expect(_type(post, "SW1A1AA").text, "SW1 1AA");
      // a digit cant fill a letter slot
      expect(_type(post, "12").text, "");
    });

    test("* takes either", () {
      final any = MaskedTextInputFormatter("**-**");
      expect(_type(any, "a1b2").text, "a1-b2");
    });
  });

  group("unmask", () {
    test("gives back only what was typed", () {
      expect(phone.unmask("555 123-4567"), "5551234567");
      expect(phone.unmask("555 1"), "5551");
      expect(phone.unmask(""), "");
    });

    test("a literal that looks like a slot character isnt returned", () {
      // the leading 1 is part of the mask, not something anybody typed
      final trunk = MaskedTextInputFormatter("1-###-####");
      final v = _type(trunk, "5551234");
      expect(v.text, "1-555-1234");
      expect(trunk.unmask(v.text), "5551234");
    });

    test("round trips through apply", () {
      const raw = "5551234567";
      expect(phone.unmask(phone.apply(raw)), raw);
    });
  });

  test("slotCount counts slots, not mask length", () {
    expect(phone.slotCount, 10);
    expect(phone.mask.length, 12);
  });
}