test.cpp

/*### Bank OCR

Your manager has recently purchased a machine that assists in reading letters and faxes sent in by branch offices. The machine scans the paper documents, and produces a file with a number of entries. You will write a program to parse this file.

#### Specification
#### User Story 1

The following format is created by the machine:
```
    _  _     _  _  _  _  _
  | _| _||_||_ |_   ||_||_|
  ||_  _|  | _||_|  ||_| _|
```
Each entry is 3 lines long, and each line has 27 characters. 3 lines of each entry contain an account number written using pipes and underscores.

Each account number should have 9 digits, all of which should be in the range 0-9. A normal file contains around 500 entries.

Write a program that can take this file and parse it into actual account numbers.

Example input and output
```
 _  _  _  _  _  _  _  _  _
| || || || || || || || || |
|_||_||_||_||_||_||_||_||_|

=> 000000000

  |  |  |  |  |  |  |  |  |
  |  |  |  |  |  |  |  |  |

=> 111111111

 _  _  _  _  _  _  _  _  _
 _| _| _| _| _| _| _| _| _|
|_ |_ |_ |_ |_ |_ |_ |_ |_

=> 222222222

 _  _  _  _  _  _  _  _  _
 _| _| _| _| _| _| _| _| _|
 _| _| _| _| _| _| _| _| _|

=> 333333333

|_||_||_||_||_||_||_||_||_|
  |  |  |  |  |  |  |  |  |

=> 444444444

 _  _  _  _  _  _  _  _  _
|_ |_ |_ |_ |_ |_ |_ |_ |_
 _| _| _| _| _| _| _| _| _|

=> 555555555

 _  _  _  _  _  _  _  _  _
|_ |_ |_ |_ |_ |_ |_ |_ |_
|_||_||_||_||_||_||_||_||_|

=> 666666666

 _  _  _  _  _  _  _  _  _
  |  |  |  |  |  |  |  |  |
  |  |  |  |  |  |  |  |  |

=> 777777777

 _  _  _  _  _  _  _  _  _
|_||_||_||_||_||_||_||_||_|
|_||_||_||_||_||_||_||_||_|

=> 888888888

 _  _  _  _  _  _  _  _  _
|_||_||_||_||_||_||_||_||_|
 _| _| _| _| _| _| _| _| _|

=> 999999999

    _  _     _  _  _  _  _
  | _| _||_||_ |_   ||_||_|
  ||_  _|  | _||_|  ||_| _|

=> 123456789
```
*/
#include <gtest/gtest.h>
#include <string>

const unsigned short g_digitLen = 3;
const unsigned short g_linesInDigit = 3;
struct Digit
{
    std::string lines[g_linesInDigit];
};

const unsigned short g_digitsOnDisplay = 9;
struct Display
{
    std::string lines[g_linesInDigit];
};

const Digit s_digit0 = { " _ ",
                         "| |",
                         "|_|"
                       };
const Digit s_digit1 = { "   ",
                         "  |",
                         "  |"
                       };
const Digit s_digit2 = { " _ ",
                         " _|",
                         "|_ "
                       };
const Digit s_digit3 = { " _ ",
                         " _|",
                         " _|"
                       };
const Digit s_digit4 = { "   ",
                         "|_|",
                         "  |"
                       };
const Digit s_digit5 = { " _ ",
                         "|_ ",
                         " _|"
                       };
const Digit s_digit6 = { " _ ",
                         "|_ ",
                         "|_|"
                       };
const Digit s_digit7 = { " _ ",
                         "  |",
                         "  |"
                       };
const Digit s_digit8 = { " _ ",
                         "|_|",
                         "|_|"
                       };
const Digit s_digit9 = { " _ ",
                         "|_|",
                         " _|"
                       };

const Display s_displayAll0 = { " _  _  _  _  _  _  _  _  _ ",
                                "| || || || || || || || || |",
                                "|_||_||_||_||_||_||_||_||_|"
};

const Display s_displayAll1 = { "                           ",
                                "  |  |  |  |  |  |  |  |  |",
                                "  |  |  |  |  |  |  |  |  |"
};

const Display s_displayAll2 = {  " _  _  _  _  _  _  _  _  _ ",
                                 " _| _| _| _| _| _| _| _| _|",
                                 "|_ |_ |_ |_ |_ |_ |_ |_ |_ "
};

const Display s_displayAll3 = { " _  _  _  _  _  _  _  _  _ ",
                                " _| _| _| _| _| _| _| _| _|",
                                " _| _| _| _| _| _| _| _| _|"
};

const Display s_displayAll4 = { "                           ",
                                "|_||_||_||_||_||_||_||_||_|",
                                "  |  |  |  |  |  |  |  |  |"
};

const Display s_displayAll5 = { " _  _  _  _  _  _  _  _  _ ",
                                "|_ |_ |_ |_ |_ |_ |_ |_ |_ ",
                                " _| _| _| _| _| _| _| _| _|"
};

const Display s_displayAll6 = { " _  _  _  _  _  _  _  _  _ ",
                                "|_ |_ |_ |_ |_ |_ |_ |_ |_ ",
                                "|_||_||_||_||_||_||_||_||_|"
};

const Display s_displayAll7 = { " _  _  _  _  _  _  _  _  _ ",
                                "  |  |  |  |  |  |  |  |  |",
                                "  |  |  |  |  |  |  |  |  |"
};

const Display s_displayAll8 = { " _  _  _  _  _  _  _  _  _ ",
                                "|_||_||_||_||_||_||_||_||_|",
                                "|_||_||_||_||_||_||_||_||_|"
};

const Display s_displayAll9 = { " _  _  _  _  _  _  _  _  _ ",
                                "|_||_||_||_||_||_||_||_||_|",
                                " _| _| _| _| _| _| _| _| _|"
};

const Display s_display123456789 = { "    _  _     _  _  _  _  _ ",
                                     "  | _| _||_||_ |_   ||_||_|",
                                     "  ||_  _|  | _||_|  ||_| _|"
};

/*
 * test list :
 * throws if empty file
 * throws if not each line 27 long
 * throws if line count mod 3 != 0
 * throws in case of invalid number form
 * successful conversation (one id)
 * successful conversation (two id's)
 * successful conversation (unlimited size)
*/

class EmptyFileError : public std::runtime_error
{
public:
    EmptyFileError(const char* what)
        : std::runtime_error(what)
    {}
};

class LenghtError : public std::runtime_error
{
public:
    LenghtError(const char* what)
        : std::runtime_error(what)
    {}
};

class LineCountError : public std::runtime_error
{
public:
    LineCountError(const char* what)
        : std::runtime_error(what)
    {}
};

class NumberFormatError : public std::runtime_error
{
public:
    NumberFormatError(const char* what)
        : std::runtime_error(what)
    {}
};

std::vector<std::string> SplitByLines(const std::string& strToSplit)
{
    std::stringstream ss(strToSplit);
    std::string item;
    std::vector<std::string> splittedStrings;
    while (std::getline(ss, item, '\n'))
    {
       if (item.size() != 27)
       {
           throw LenghtError("OOPS");
       }

       splittedStrings.push_back(item);
    }
    return splittedStrings;
}

bool operator == (const Digit& lhs, const Digit& rhs)
{
    bool equals = true;
    for (size_t i = 0; i < 3; ++i)
    {
        equals = equals && lhs.lines[i] == rhs.lines[i];
    }

    return equals;
}

size_t GetDigit(const Digit& digit)
{
    if (digit == s_digit0)
    {
        return 0;
    }
    if (digit == s_digit1)
    {
        return 1;
    }
    if (digit == s_digit2)
    {
        return 2;
    }
    if (digit == s_digit3)
    {
        return 3;
    }
    if (digit == s_digit4)
    {
        return 4;
    }
    if (digit == s_digit5)
    {
        return 5;
    }
    if (digit == s_digit6)
    {
        return 6;
    }
    if (digit == s_digit7)
    {
        return 7;
    }
    if (digit == s_digit8)
    {
        return 8;
    }
    if (digit == s_digit9)
    {
        return 9;
    }

    throw NumberFormatError("OOPS");
}
std::string GetNumberFromThreeStrings(const std::string& first, const std::string& second, const std::string& third)
{
    std::stringstream stream;
    size_t pos = 0;
    while (pos < 27)
    {
        Digit digit;
        digit.lines[0] = first.substr(pos, 3);
        digit.lines[1] = second.substr(pos, 3);
        digit.lines[2] = third.substr(pos, 3);
        stream << GetDigit(digit);
        pos += 3;
    }

    return stream.str();
}

std::vector<std::string> SplitByNumbers(const std::vector<std::string>& lines)
{
    std::vector<std::string> numbers;
    for (size_t i = 0; i < lines.size() / 3; ++i)
    {
        std::string firstLine = lines[3*i];
        std::string secondLine = lines[3*i + 1];
        std::string thirdLine = lines[3*i + 2];
        numbers.push_back(GetNumberFromThreeStrings(firstLine, secondLine, thirdLine));
    }

    return numbers;
}

std::vector<std::string> ParseFile(const std::string& file)
{
    if (file.empty())
    {
        throw EmptyFileError("empty file");
    }

    std::vector<std::string> lines = SplitByLines(file);

    if (lines.size() % 3 != 0)
    {
        throw LineCountError("line count error");
    }

    return SplitByNumbers(lines);
}

TEST(ParseFile, ThrowsIfEmptyFile)
{
    ASSERT_THROW(ParseFile(""), EmptyFileError);
}

TEST(ParseFile, ThrowsIfNotEachLine27Long)
{
    ASSERT_THROW(ParseFile("abc"), LenghtError);
}

TEST(ParseFile, ThrowsIfLineCountMod3NotZero)
{
    std::string file(27, '_');
    file = file + '\n' + file;
    ASSERT_THROW(ParseFile(file), LineCountError);
}

TEST(SplitByNumbers, ThrowsInCaseOfInvalidNumberForm)
{
    std::string file(27, '_');
    file = file + '\n' + file + '\n' + file;
    std::vector<std::string> files {file, file, file};
    ASSERT_THROW(SplitByNumbers(files), NumberFormatError);
}

TEST(SplitByNumbers, SuccessfulSplit)
{
    std::vector<std::string> lines = {s_display123456789.lines[0], s_display123456789.lines[1], s_display123456789.lines[2]};
    auto result = SplitByNumbers(lines);
    ASSERT_EQ(result.size(), 1);
    ASSERT_EQ(result[0], "123456789");
}

TEST(ParseFile, SuccessfulParse)
{
    std::string file = s_display123456789.lines[0] + "\n" + s_display123456789.lines[1] + "\n" + s_display123456789.lines[2];
    std::vector<std::string> result = ParseFile(file);
    ASSERT_EQ(result[0], "123456789");
}