<?php

namespace lib\Database;

use PDO;

class QueryBuilder
{
  private PDO $pdo;
  private string $table = '';
  private array $select = ['*'];
  private array $where = [];
  private array $bindings = [];
  private array $order = [];
  private ?int $limit = null;
  private ?int $offset = null;
  private array $joins = [];

  public function __construct(PDO $pdo)
  {
    $this->pdo = $pdo;
  }

  public function table(string $table): static
  {
    $this->table = $table;
    return $this;
  }

  public function select(array|string $columns): static
  {
    $this->select = is_array($columns) ? $columns : explode(',', $columns);
    return $this;
  }

  public function where(string $column, string $operator = "", mixed $value = ""): static
  {
    $placeholder = ':w_' . count($this->bindings);
    $this->where[] = "$column $operator $placeholder";
    $this->bindings[$placeholder] = $value;
    return $this;
  }

  public function orderBy(string $column, string $direction = 'ASC'): static
  {
    $this->order[] = "$column $direction";
    return $this;
  }

  public function limit(int $limit): static
  {
    $this->limit = $limit;
    return $this;
  }

  public function offset(int $offset): static
  {
    $this->offset = $offset;
    return $this;
  }

  public function when(bool $condition, callable $callback): static
  {
    if ($condition) {
      $callback($this);
    }
    return $this;
  }

  public function rawWhere(string $expression, array $bindings = []): static
  {
    $this->where[] = "($expression)";
    foreach ($bindings as $key => $value) {
      $this->bindings[":raw_" . $key] = $value;
    }
    return $this;
  }

  public function get(): array
  {
    $sql = "SELECT " . implode(', ', $this->select) . " FROM {$this->table}";

    if (!empty($this->where)) {
      $sql .= " WHERE " . implode(' AND ', $this->where);
    }

    if (!empty($this->order)) {
      $sql .= " ORDER BY " . implode(', ', $this->order);
    }

    if (!is_null($this->limit)) {
      $sql .= " LIMIT :__limit";
      $this->bindings[':__limit'] = $this->limit;
    }

    if (!is_null($this->offset)) {
      $sql .= " OFFSET :__offset";
      $this->bindings[':__offset'] = $this->offset;
    }

    $stmt = $this->pdo->prepare($sql);
    foreach ($this->bindings as $placeholder => $value) {
      $stmt->bindValue($placeholder, $value);
    }

    $stmt->execute();
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
  }

  public function first(): ?array
  {
    $this->limit(1);
    $rows = $this->get();
    return $rows[0] ?? null;
  }

  public function count(): int
  {
    $this->select = ['COUNT(*) AS cnt'];
    $results = $this->get();
    return (int)($results[0]['cnt'] ?? 0);
  }

  public function exists(): bool
  {
    return $this->count() > 0;
  }

  public function insert(array $data): bool
  {
    $columns = array_keys($data);
    $placeholders = array_map(fn($col) => ':' . $col, $columns);

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

    foreach ($data as $col => $value) {
      $stmt->bindValue(':' . $col, $value);
    }

    return $stmt->execute();
  }

  public function update(array $data): bool
  {
    if (empty($this->where)) {
      throw new \Exception("Update without WHERE is not allowed.");
    }

    $setClauses = [];
    foreach ($data as $col => $val) {
      $placeholder = ':u_' . $col;
      $setClauses[] = "$col = $placeholder";
      $this->bindings[$placeholder] = $val;
    }

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

    if (!empty($this->where)) {
      $sql .= " WHERE " . implode(' AND ', $this->where);
    }

    $stmt = $this->pdo->prepare($sql);
    foreach ($this->bindings as $placeholder => $value) {
      $stmt->bindValue($placeholder, $value);
    }

    return $stmt->execute();
  }

  public function delete(): bool
  {
    if (empty($this->where)) {
      throw new \Exception("Delete without WHERE is not allowed.");
    }

    $sql = "DELETE FROM {$this->table} WHERE " . implode(' AND ', $this->where);
    $stmt = $this->pdo->prepare($sql);
    foreach ($this->bindings as $placeholder => $value) {
      $stmt->bindValue($placeholder, $value);
    }

    return $stmt->execute();
  }

  public function whereIn(string $column, array $values, string $boolean = 'AND'): static
  {
    if (empty($values)) {
      throw new \InvalidArgumentException("whereIn: values 배열이 비어있을 수 없습니다.");
    }

    $placeholders = implode(', ', array_fill(0, count($values), '?'));
    $this->where[] = "$column IN ($placeholders)";
    $this->bindings = array_merge($this->bindings, $values);

    return $this;
  }

  public function whereNotIn(string $column, array $values, string $boolean = 'AND'): static
  {
    if (empty($values)) {
      throw new \InvalidArgumentException("whereNotIn: values 배열이 비어있을 수 없습니다.");
    }

    $placeholders = implode(', ', array_fill(0, count($values), '?'));
    $this->where[] = "$column NOT IN ($placeholders)";
    $this->bindings = array_merge($this->bindings, $values);

    return $this;
  }

  public function orWhereIn(string $column, array $values): static
  {
    return $this->whereIn($column, $values, 'OR');
  }

  public function orWhere(string $column, string $operator, mixed $value): static
  {
    $placeholder = ':w_' . count($this->bindings);
    $condition = "$column $operator $placeholder";

    if (empty($this->where)) {
      $this->where[] = $condition;
    } else {
      $last = array_pop($this->where);
      $this->where[] = "($last OR $condition)";
    }

    $this->bindings[$placeholder] = $value;
    return $this;
  }

  public function join(string $table, string $on, string $type = 'INNER'): static
  {
    $this->joins[] = strtoupper($type) . " JOIN $table ON $on";
    return $this;
  }

  public function raw(string $sql, array $bindings = []): array
  {
    $stmt = $this->pdo->prepare($sql);
    foreach ($bindings as $key => $value) {
      $stmt->bindValue(is_int($key) ? $key + 1 : $key, $value);
    }
    $stmt->execute();
    return $stmt->fetchAll(PDO::FETCH_ASSOC);
  }

  public function beginTransaction(): void
  {
    $this->pdo->beginTransaction();
  }

  public function commit(): void
  {
    $this->pdo->commit();
  }

  public function rollBack(): void
  {
    if ($this->pdo->inTransaction()) {
      $this->pdo->rollBack();
    }
  }
}