<?php
/**
 * WorkflowModel - Handles status transition workflows and validation
 */
class WorkflowModel {
    private $conn;

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

    /**
     * Get allowed status transitions for a given status
     *
     * @param string $currentStatus Current ticket status
     * @return array Array of allowed transitions with requirements
     */
    public function getAllowedTransitions($currentStatus) {
        $sql = "SELECT to_status, requires_comment, requires_admin
                FROM status_transitions
                WHERE from_status = ? AND is_active = TRUE";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("s", $currentStatus);
        $stmt->execute();
        $result = $stmt->get_result();

        $transitions = [];
        while ($row = $result->fetch_assoc()) {
            $transitions[] = $row;
        }

        $stmt->close();
        return $transitions;
    }

    /**
     * Check if a status transition is allowed
     *
     * @param string $fromStatus Current status
     * @param string $toStatus Desired status
     * @param bool $isAdmin Whether user is admin
     * @return bool True if transition is allowed
     */
    public function isTransitionAllowed($fromStatus, $toStatus, $isAdmin = false) {
        // Allow same status (no change)
        if ($fromStatus === $toStatus) {
            return true;
        }

        $sql = "SELECT requires_admin FROM status_transitions
                WHERE from_status = ? AND to_status = ? AND is_active = TRUE";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("ss", $fromStatus, $toStatus);
        $stmt->execute();
        $result = $stmt->get_result();

        if ($result->num_rows === 0) {
            $stmt->close();
            return false; // Transition not defined
        }

        $row = $result->fetch_assoc();
        $stmt->close();

        if ($row['requires_admin'] && !$isAdmin) {
            return false; // Admin required
        }

        return true;
    }

    /**
     * Get all possible statuses from transitions table
     *
     * @return array Array of unique status values
     */
    public function getAllStatuses() {
        $sql = "SELECT DISTINCT from_status as status FROM status_transitions
                UNION
                SELECT DISTINCT to_status as status FROM status_transitions
                ORDER BY status";
        $result = $this->conn->query($sql);

        $statuses = [];
        while ($row = $result->fetch_assoc()) {
            $statuses[] = $row['status'];
        }

        return $statuses;
    }

    /**
     * Get transition requirements
     *
     * @param string $fromStatus Current status
     * @param string $toStatus Desired status
     * @return array|null Transition requirements or null if not found
     */
    public function getTransitionRequirements($fromStatus, $toStatus) {
        $sql = "SELECT requires_comment, requires_admin
                FROM status_transitions
                WHERE from_status = ? AND to_status = ? AND is_active = TRUE";
        $stmt = $this->conn->prepare($sql);
        $stmt->bind_param("ss", $fromStatus, $toStatus);
        $stmt->execute();
        $result = $stmt->get_result();

        if ($result->num_rows === 0) {
            $stmt->close();
            return null;
        }

        $row = $result->fetch_assoc();
        $stmt->close();
        return $row;
    }
}