<?php

/**
 * ParseDateString.php
 * Copyright (c) 2020 james@firefly-iii.org
 *
 * This file is part of Firefly III (https://github.com/firefly-iii).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

declare(strict_types=1);

namespace FireflyIII\Support;

use Carbon\Carbon;
use Carbon\CarbonInterface;
use Carbon\Exceptions\InvalidFormatException;
use FireflyIII\Exceptions\FireflyException;
use Illuminate\Support\Facades\Log;
use Safe\Exceptions\PcreException;

use function Safe\preg_match;

/**
 * Class ParseDateString
 */
class ParseDateString
{
    private array $keywords = [
        'today',
        'yesterday',
        'tomorrow',
        'start of this week',
        'end of this week',
        'start of this month',
        'end of this month',
        'start of this quarter',
        'end of this quarter',
        'start of this year',
        'end of this year',
    ];

    public function isDateRange(string $date): bool
    {
        $date = strtolower($date);
        // not 10 chars:
        if (10 !== strlen($date)) {
            return false;
        }
        // all x'es
        if ('xxxx-xx-xx' === strtolower($date)) {
            return false;
        }

        // no x'es
        return !(!str_contains($date, 'xx') && !str_contains($date, 'xxxx'));
    }

    /**
     * @throws FireflyException
     * @throws PcreException
     *
     * @SuppressWarnings("PHPMD.NPathComplexity")
     */
    public function parseDate(string $date): Carbon
    {
        Log::debug(sprintf('parseDate("%s")', $date));
        $date        = strtolower($date);
        // parse keywords:
        if (in_array($date, $this->keywords, true)) {
            return $this->parseKeyword($date);
        }

        // if regex for YYYY-MM-DD:
        $pattern     = '/^(19|20)\d\d-(0[1-9]|1[012])-(0[1-9]|[12]\d|3[01])$/';
        $result      = preg_match($pattern, $date);
        if (0 !== $result) {
            return $this->parseDefaultDate($date);
        }

        // if + or -:
        if (str_starts_with($date, '+') || str_starts_with($date, '-')) {
            return $this->parseRelativeDate($date);
        }
        if ('xxxx-xx-xx' === strtolower($date)) {
            throw new FireflyException(sprintf('[a] Not a recognised date format: "%s"', $date));
        }
        // can't do a partial year:
        $substrCount = substr_count(substr($date, 0, 4), 'x');
        if (10 === strlen($date) && $substrCount > 0 && $substrCount < 4) {
            throw new FireflyException(sprintf('[b] Not a recognised date format: "%s"', $date));
        }

        // maybe a date range
        if (10 === strlen($date) && (str_contains($date, 'xx') || str_contains($date, 'xxxx'))) {
            Log::debug(sprintf('[c] Detected a date range ("%s"), return a fake date.', $date));

            // very lazy way to parse the date without parsing it, because this specific function
            // cant handle date ranges.
            return new Carbon('1984-09-17');
        }
        // maybe a year, nothing else?
        if (4 === strlen($date) && is_numeric($date) && (int) $date > 1000 && (int) $date <= 3000) {
            return new Carbon(sprintf('%d-01-01', $date));
        }

        throw new FireflyException(sprintf('[d] Not a recognised date format: "%s"', $date));
    }

    public function parseRange(string $date): array
    {
        // several types of range can be submitted
        $result = ['exact' => new Carbon('1984-09-17')];

        switch (true) {
            default:
                break;

            case $this->isDayRange($date):
                $result = $this->parseDayRange($date);

                break;

            case $this->isMonthRange($date):
                $result = $this->parseMonthRange($date);

                break;

            case $this->isYearRange($date):
                $result = $this->parseYearRange($date);

                break;

            case $this->isMonthDayRange($date):
                $result = $this->parseMonthDayRange($date);

                break;

            case $this->isDayYearRange($date):
                $result = $this->parseDayYearRange($date);

                break;

            case $this->isMonthYearRange($date):
                $result = $this->parseMonthYearRange($date);

                break;
        }

        return $result;
    }

    /**
     * Returns true if this matches regex for xxxx-xx-DD:
     */
    protected function isDayRange(string $date): bool
    {
        $pattern = '/^xxxx-xx-(0[1-9]|[12]\d|3[01])$/';
        $result  = preg_match($pattern, $date);
        if (0 !== $result) {
            Log::debug(sprintf('"%s" is a day range.', $date));

            return true;
        }
        Log::debug(sprintf('"%s" is not a day range.', $date));

        return false;
    }

    protected function isDayYearRange(string $date): bool
    {
        // if regex for YYYY-xx-DD:
        $pattern = '/^(19|20)\d\d-xx-(0[1-9]|[12]\d|3[01])$/';
        $result  = preg_match($pattern, $date);
        if (0 !== $result) {
            Log::debug(sprintf('"%s" is a day/year range.', $date));

            return true;
        }
        Log::debug(sprintf('"%s" is not a day/year range.', $date));

        return false;
    }

    protected function isMonthDayRange(string $date): bool
    {
        // if regex for xxxx-MM-DD:
        $pattern = '/^xxxx-(0[1-9]|1[012])-(0[1-9]|[12]\d|3[01])$/';
        $result  = preg_match($pattern, $date);
        if (0 !== $result) {
            Log::debug(sprintf('"%s" is a month/day range.', $date));

            return true;
        }
        Log::debug(sprintf('"%s" is not a month/day range.', $date));

        return false;
    }

    protected function isMonthRange(string $date): bool
    {
        // if regex for xxxx-MM-xx:
        $pattern = '/^xxxx-(0[1-9]|1[012])-xx$/';
        $result  = preg_match($pattern, $date);
        if (0 !== $result) {
            Log::debug(sprintf('"%s" is a month range.', $date));

            return true;
        }
        Log::debug(sprintf('"%s" is not a month range.', $date));

        return false;
    }

    protected function isMonthYearRange(string $date): bool
    {
        // if regex for YYYY-MM-xx:
        $pattern = '/^(19|20)\d\d-(0[1-9]|1[012])-xx$/';
        $result  = preg_match($pattern, $date);
        if (0 !== $result) {
            Log::debug(sprintf('"%s" is a month/year range.', $date));

            return true;
        }
        Log::debug(sprintf('"%s" is not a month/year range.', $date));

        return false;
    }

    protected function isYearRange(string $date): bool
    {
        // if regex for YYYY-xx-xx:
        $pattern = '/^(19|20)\d\d-xx-xx$/';
        $result  = preg_match($pattern, $date);
        if (0 !== $result) {
            Log::debug(sprintf('"%s" is a year range.', $date));

            return true;
        }
        Log::debug(sprintf('"%s" is not a year range.', $date));

        return false;
    }

    /**
     * format of string is xxxx-xx-DD
     */
    protected function parseDayRange(string $date): array
    {
        $parts = explode('-', $date);

        return ['day' => $parts[2]];
    }

    protected function parseDefaultDate(string $date): Carbon
    {
        $result = false;

        try {
            $result = Carbon::createFromFormat('Y-m-d', $date);
        } catch (InvalidFormatException $e) {
            Log::error(sprintf('parseDefaultDate("%s") ran into an error, but dont mind: %s', $date, $e->getMessage()));
        }
        if (false === $result) {
            return today(config('app.timezone'))->startOfDay();
        }

        return $result;
    }

    protected function parseKeyword(string $keyword): Carbon
    {
        $today = today(config('app.timezone'))->startOfDay();

        return match ($keyword) {
            default                 => $today,
            'yesterday'             => $today->subDay(),
            'tomorrow'              => $today->addDay(),
            'start of this week'    => $today->startOfWeek(CarbonInterface::MONDAY),
            'end of this week'      => $today->endOfWeek(CarbonInterface::SUNDAY),
            'start of this month'   => $today->startOfMonth(),
            'end of this month'     => $today->endOfMonth(),
            'start of this quarter' => $today->startOfQuarter(),
            'end of this quarter'   => $today->endOfQuarter(),
            'start of this year'    => $today->startOfYear(),
            'end of this year'      => $today->endOfYear()
        };
    }

    /**
     * format of string is xxxx-MM-xx
     */
    protected function parseMonthRange(string $date): array
    {
        Log::debug(sprintf('parseMonthRange: Parsed "%s".', $date));
        $parts = explode('-', $date);

        return ['month' => $parts[1]];
    }

    /**
     * format of string is YYYY-MM-xx
     */
    protected function parseMonthYearRange(string $date): array
    {
        Log::debug(sprintf('parseMonthYearRange: Parsed "%s".', $date));
        $parts = explode('-', $date);

        return ['year'  => $parts[0], 'month' => $parts[1]];
    }

    protected function parseRelativeDate(string $date): Carbon
    {
        Log::debug(sprintf('Now in parseRelativeDate("%s")', $date));
        $parts     = explode(' ', $date);
        $today     = today(config('app.timezone'))->startOfDay();
        $functions = [
            ['d' => 'subDays', 'w' => 'subWeeks', 'm' => 'subMonths', 'q' => 'subQuarters', 'y' => 'subYears'],
            ['d' => 'addDays', 'w' => 'addWeeks', 'm' => 'addMonths', 'q' => 'addQuarters', 'y' => 'addYears'],
        ];

        foreach ($parts as $part) {
            Log::debug(sprintf('Now parsing part "%s"', $part));
            $part      = trim($part);

            // verify if correct
            $pattern   = '/[+-]\d+[wqmdy]/';
            $result    = preg_match($pattern, $part);
            if (0 === $result) {
                Log::error(sprintf('Part "%s" does not match regular expression. Will be skipped.', $part));

                continue;
            }
            $direction = str_starts_with($part, '+') ? 1 : 0;
            $period    = $part[strlen($part) - 1];
            $number    = (int) substr($part, 1, -1);
            if (!array_key_exists($period, $functions[$direction])) {
                Log::error(sprintf('No method for direction %d and period "%s".', $direction, $period));

                continue;
            }
            $func      = $functions[$direction][$period];
            Log::debug(sprintf('Will now do %s(%d) on %s', $func, $number, $today->format('Y-m-d')));
            $today->{$func}($number);
            Log::debug(sprintf('Resulting date is %s', $today->format('Y-m-d')));
        }

        return $today;
    }

    /**
     * format of string is YYYY-xx-xx
     */
    protected function parseYearRange(string $date): array
    {
        Log::debug(sprintf('parseYearRange: Parsed "%s"', $date));
        $parts = explode('-', $date);

        return ['year' => $parts[0]];
    }

    /**
     * format of string is YYYY-xx-DD
     */
    private function parseDayYearRange(string $date): array
    {
        Log::debug(sprintf('parseDayYearRange: Parsed "%s".', $date));
        $parts = explode('-', $date);

        return ['year' => $parts[0], 'day'  => $parts[2]];
    }

    /**
     * format of string is xxxx-MM-DD
     */
    private function parseMonthDayRange(string $date): array
    {
        Log::debug(sprintf('parseMonthDayRange: Parsed "%s".', $date));
        $parts = explode('-', $date);

        return ['month' => $parts[1], 'day'   => $parts[2]];
    }
}
