<?php declare(strict_types=1);

namespace BitBadger\PDODocument;

/**
 * Criteria for a field WHERE clause
 */
class Field
{
    /**
     * Constructor
     *
     * NOTE: Use static construction methods rather than using this directly; different properties are required
     *       depending on the operation being performed. This is only public so it can be tested.
     *
     * @param string $fieldName The name of the field
     * @param Op $op The operation by which the field will be compared
     * @param mixed $value The value of the field
     * @param string $paramName The name of the parameter to which this should be bound
     * @param string $qualifier A table qualifier for the `data` column
     */
    public function __construct(public string $fieldName = '', public Op $op = Op::EQ, public mixed $value = '',
                                public string $paramName = '', public string $qualifier = '') { }

    /**
     * Append the parameter name and value to the given associative array
     *
     * @param array $existing The existing parameters
     * @return array The given parameter array with this field's name and value appended
     */
    public function appendParameter(array $existing): array
    {
        switch ($this->op) {
            case Op::EX:
            case Op::NEX:
                break;
            case Op::BT:
                $existing["{$this->paramName}min"] = $this->value[0];
                $existing["{$this->paramName}max"] = $this->value[1];
                break;
            default:
                $existing[$this->paramName] = $this->value;
        }
        return $existing;
    }

    /**
     * Get the WHERE clause fragment for this parameter
     *
     * @return string The WHERE clause fragment for this parameter
     * @throws DocumentException If the database mode has not been set
     */
    public function toWhere(): string
    {
        $criteria = match ($this->op) {
            Op::EX, Op::NEX => '',
            Op::BT          => " {$this->paramName}min AND {$this->paramName}max",
            default         => " $this->paramName"
        };
        $prefix = $this->qualifier == '' ? '' : "$this->qualifier.";
        $fieldPath = match (Configuration::$mode) {
            Mode::SQLite => "{$prefix}data->>'"
                . (str_contains($this->fieldName, '.')
                    ? implode("'->>'", explode('.', $this->fieldName))
                    : $this->fieldName)
                . "'",
            Mode::PgSQL => $this->op == Op::BT && is_numeric($this->value[0])
                ? "({$prefix}data->>'$this->fieldName')::numeric"
                : "{$prefix}data->>'$this->fieldName'",
            default => throw new DocumentException('Database mode not set; cannot make field WHERE clause')
        };
        return $fieldPath . ' ' . $this->op->toString() . $criteria;
    }

    /**
     * Create an equals (=) field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $value The value for which equality will be checked
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function EQ(string $fieldName, mixed $value, string $paramName = ''): static
    {
        return new static($fieldName, Op::EQ, $value, $paramName);
    }

    /**
     * Create a greater than (>) field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $value The value for the greater than comparison
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function GT(string $fieldName, mixed $value, string $paramName = ''): static
    {
        return new static($fieldName, Op::GT, $value, $paramName);
    }

    /**
     * Create a greater than or equal to (>=) field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $value The value for the greater than or equal to comparison
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function GE(string $fieldName, mixed $value, string $paramName = ''): static
    {
        return new static($fieldName, Op::GE, $value, $paramName);
    }

    /**
     * Create a less than (<) field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $value The value for the less than comparison
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function LT(string $fieldName, mixed $value, string $paramName = ''): static
    {
        return new static($fieldName, Op::LT, $value, $paramName);
    }

    /**
     * Create a less than or equal to (<=) field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $value The value for the less than or equal to comparison
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function LE(string $fieldName, mixed $value, string $paramName = ''): static
    {
        return new static($fieldName, Op::LE, $value, $paramName);
    }

    /**
     * Create a not equals (<>) field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $value The value for the not equals comparison
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function NE(string $fieldName, mixed $value, string $paramName = ''): static
    {
        return new static($fieldName, Op::NE, $value, $paramName);
    }

    /**
     * Create a BETWEEN field criterion
     *
     * @param string $fieldName The name of the field against which the value will be compared
     * @param mixed $minValue The lower value for range
     * @param mixed $maxValue The upper value for the range
     * @param string $paramName The name of the parameter to which this should be bound (optional; generated if blank)
     * @return static The field with the requested criterion
     */
    public static function BT(string $fieldName, mixed $minValue, mixed $maxValue, string $paramName = ''): static
    {
        return new static($fieldName, Op::BT, [$minValue, $maxValue], $paramName);
    }

    /**
     * Create an exists (IS NOT NULL) field criterion
     *
     * @param string $fieldName The name of the field for which existence will be checked
     * @return static The field with the requested criterion
     */
    public static function EX(string $fieldName): static
    {
        return new static($fieldName, Op::EX, '', '');
    }

    /**
     * Create a not exists (IS NULL) field criterion
     *
     * @param string $fieldName The name of the field for which non-existence will be checked
     * @return static The field with the requested criterion
     */
    public static function NEX(string $fieldName): static
    {
        return new static($fieldName, Op::NEX, '', '');
    }
}