<?php

namespace App\Core\Database;

/**
 * NovaCore Query Builder
 * Simple query builder for database operations
 */
class QueryBuilder
{
    private Connection $connection;
    private string $table;
    private array $select = ['*'];
    private array $where = [];
    private array $orderBy = [];
    private array $groupBy = [];
    private array $having = [];
    private ?int $limit = null;
    private ?int $offset = null;
    private array $joins = [];

    public function __construct(Connection $connection, string $table)
    {
        $this->connection = $connection;
        $this->table = $table;
    }

    /**
     * Select columns
     */
    public function select(array $columns): self
    {
        $this->select = $columns;
        return $this;
    }

    /**
     * Add where condition
     */
    public function where(string $column, $operator, $value = null): self
    {
        if ($value === null) {
            $value = $operator;
            $operator = '=';
        }

        $this->where[] = [
            'column' => $column,
            'operator' => $operator,
            'value' => $value,
            'boolean' => 'AND'
        ];

        return $this;
    }

    /**
     * Add OR where condition
     */
    public function orWhere(string $column, $operator, $value = null): self
    {
        if ($value === null) {
            $value = $operator;
            $operator = '=';
        }

        $this->where[] = [
            'column' => $column,
            'operator' => $operator,
            'value' => $value,
            'boolean' => 'OR'
        ];

        return $this;
    }

    /**
     * Add where in condition
     */
    public function whereIn(string $column, array $values): self
    {
        $this->where[] = [
            'column' => $column,
            'operator' => 'IN',
            'value' => $values,
            'boolean' => 'AND'
        ];

        return $this;
    }

    /**
     * Add where not in condition
     */
    public function whereNotIn(string $column, array $values): self
    {
        $this->where[] = [
            'column' => $column,
            'operator' => 'NOT IN',
            'value' => $values,
            'boolean' => 'AND'
        ];

        return $this;
    }

    /**
     * Add where null condition
     */
    public function whereNull(string $column): self
    {
        $this->where[] = [
            'column' => $column,
            'operator' => 'IS NULL',
            'value' => null,
            'boolean' => 'AND'
        ];

        return $this;
    }

    /**
     * Add where not null condition
     */
    public function whereNotNull(string $column): self
    {
        $this->where[] = [
            'column' => $column,
            'operator' => 'IS NOT NULL',
            'value' => null,
            'boolean' => 'AND'
        ];

        return $this;
    }

    /**
     * Add order by clause
     */
    public function orderBy(string $column, string $direction = 'ASC'): self
    {
        $this->orderBy[] = [
            'column' => $column,
            'direction' => strtoupper($direction)
        ];

        return $this;
    }

    /**
     * Add group by clause
     */
    public function groupBy(string $column): self
    {
        $this->groupBy[] = $column;
        return $this;
    }

    /**
     * Add having clause
     */
    public function having(string $column, $operator, $value): self
    {
        $this->having[] = [
            'column' => $column,
            'operator' => $operator,
            'value' => $value,
            'boolean' => 'AND'
        ];

        return $this;
    }

    /**
     * Add limit clause
     */
    public function limit(int $limit): self
    {
        $this->limit = $limit;
        return $this;
    }

    /**
     * Add offset clause
     */
    public function offset(int $offset): self
    {
        $this->offset = $offset;
        return $this;
    }

    /**
     * Add join clause
     */
    public function join(string $table, string $first, string $operator, string $second, string $type = 'INNER'): self
    {
        $this->joins[] = [
            'table' => $table,
            'first' => $first,
            'operator' => $operator,
            'second' => $second,
            'type' => $type
        ];

        return $this;
    }

    /**
     * Add left join clause
     */
    public function leftJoin(string $table, string $first, string $operator, string $second): self
    {
        return $this->join($table, $first, $operator, $second, 'LEFT');
    }

    /**
     * Add right join clause
     */
    public function rightJoin(string $table, string $first, string $operator, string $second): self
    {
        return $this->join($table, $first, $operator, $second, 'RIGHT');
    }

    /**
     * Get all results
     */
    public function get(): array
    {
        $sql = $this->toSql();
        $params = $this->getBindings();

        return $this->connection->fetchAll($sql, $params);
    }

    /**
     * Get first result
     */
    public function first(): ?array
    {
        $this->limit(1);
        $sql = $this->toSql();
        $params = $this->getBindings();

        return $this->connection->fetch($sql, $params);
    }

    /**
     * Get count
     */
    public function count(): int
    {
        $this->select = ['COUNT(*) as count'];
        $result = $this->first();
        return (int) $result['count'];
    }

    /**
     * Insert data
     */
    public function insert(array $data): int
    {
        $columns = array_keys($data);
        $values = array_values($data);
        $placeholders = array_fill(0, count($values), '?');

        $sql = "INSERT INTO {$this->table} (" . implode(', ', $columns) . ") VALUES (" . implode(', ', $placeholders) . ")";

        return $this->connection->execute($sql, $values);
    }

    /**
     * Update data
     */
    public function update(array $data): int
    {
        $columns = array_keys($data);
        $values = array_values($data);
        $set = [];

        foreach ($columns as $column) {
            $set[] = "{$column} = ?";
        }

        $sql = "UPDATE {$this->table} SET " . implode(', ', $set);
        $params = $values;

        if (!empty($this->where)) {
            $sql .= " WHERE " . $this->buildWhereClause();
            $params = array_merge($params, $this->getWhereBindings());
        }

        return $this->connection->execute($sql, $params);
    }

    /**
     * Delete records
     */
    public function delete(): int
    {
        $sql = "DELETE FROM {$this->table}";
        $params = [];

        if (!empty($this->where)) {
            $sql .= " WHERE " . $this->buildWhereClause();
            $params = $this->getWhereBindings();
        }

        return $this->connection->execute($sql, $params);
    }

    /**
     * Build SQL query
     */
    private function toSql(): string
    {
        $sql = "SELECT " . implode(', ', $this->select) . " FROM {$this->table}";

        // Add joins
        foreach ($this->joins as $join) {
            $sql .= " {$join['type']} JOIN {$join['table']} ON {$join['first']} {$join['operator']} {$join['second']}";
        }

        // Add where clause
        if (!empty($this->where)) {
            $sql .= " WHERE " . $this->buildWhereClause();
        }

        // Add group by clause
        if (!empty($this->groupBy)) {
            $sql .= " GROUP BY " . implode(', ', $this->groupBy);
        }

        // Add having clause
        if (!empty($this->having)) {
            $sql .= " HAVING " . $this->buildHavingClause();
        }

        // Add order by clause
        if (!empty($this->orderBy)) {
            $orderBy = [];
            foreach ($this->orderBy as $order) {
                $orderBy[] = "{$order['column']} {$order['direction']}";
            }
            $sql .= " ORDER BY " . implode(', ', $orderBy);
        }

        // Add limit clause
        if ($this->limit !== null) {
            $sql .= " LIMIT {$this->limit}";
        }

        // Add offset clause
        if ($this->offset !== null) {
            $sql .= " OFFSET {$this->offset}";
        }

        return $sql;
    }

    /**
     * Build where clause
     */
    private function buildWhereClause(): string
    {
        $clauses = [];

        foreach ($this->where as $index => $condition) {
            $clause = '';

            if ($index > 0) {
                $clause .= " {$condition['boolean']} ";
            }

            if ($condition['operator'] === 'IN' || $condition['operator'] === 'NOT IN') {
                $placeholders = array_fill(0, count($condition['value']), '?');
                $clause .= "{$condition['column']} {$condition['operator']} (" . implode(', ', $placeholders) . ")";
            } else {
                $clause .= "{$condition['column']} {$condition['operator']} ?";
            }

            $clauses[] = $clause;
        }

        return implode('', $clauses);
    }

    /**
     * Build having clause
     */
    private function buildHavingClause(): string
    {
        $clauses = [];

        foreach ($this->having as $index => $condition) {
            $clause = '';

            if ($index > 0) {
                $clause .= " {$condition['boolean']} ";
            }

            $clause .= "{$condition['column']} {$condition['operator']} ?";
            $clauses[] = $clause;
        }

        return implode('', $clauses);
    }

    /**
     * Get all bindings
     */
    private function getBindings(): array
    {
        $bindings = [];

        // Add where bindings
        $bindings = array_merge($bindings, $this->getWhereBindings());

        // Add having bindings
        foreach ($this->having as $condition) {
            $bindings[] = $condition['value'];
        }

        return $bindings;
    }

    /**
     * Get where bindings
     */
    private function getWhereBindings(): array
    {
        $bindings = [];

        foreach ($this->where as $condition) {
            if ($condition['operator'] === 'IN' || $condition['operator'] === 'NOT IN') {
                $bindings = array_merge($bindings, $condition['value']);
            } else {
                $bindings[] = $condition['value'];
            }
        }

        return $bindings;
    }
}