<?php
namespace nulib\mail;

use nulib\cv;
use nulib\str;
use nulib\ValueException;
use Symfony\Component\ExpressionLanguage\ExpressionLanguage;

class MailTemplate {
  const SCHEMA = [
    "subject" => "string",
    "body" => "string",
    "exprs" => "array",
  ];

  function __construct(array $mail) {
    $tsubject = $mail["subject"] ?? null;
    $tbody = $mail["body"] ?? null;
    $texprs = $mail["exprs"] ?? [];

    $this->el = new ExpressionLanguage();
    ValueException::check_null($this->subject = $tsubject, "subject");
    ValueException::check_null($this->body = $tbody, "body");
    $exprs = [];
    # Commencer par extraire les expressions de la forme {name}
    if (preg_match_all('/\{([a-zA-Z_][a-zA-Z0-9_.-]*)}/', $this->body, $mss, PREG_SET_ORDER)) {
      foreach ($mss as $ms) {
        $key = $ms[0];
        $expr = str_replace("'", "\\'", $ms[1]);
        $expr = "_helper.value('$expr')";
        $exprs[$key] = $expr;
      }
    }
    $index = 0;
    foreach ($texprs as $key => $expr) {
      $prefix = null;
      $orig = $expr;
      if (preg_match('/^\[([^]]*)]/', $expr, $ms)) {
        # un préfixe spécifié de la forme [prefix]expr permet de reconnaitre les
        # formes spéciales de expr (+, *, .) qui sont précédées de prefix
        # exemple: [https://]+app.url permettra d'utiliser un texte markdown
        # de la forme <https://+app.url> qui est correctement reconnu comme un
        # url
        $prefix = $ms[1];
        $expr = substr($expr, strlen($ms[0]));
      }
      $mapKey = false;
      if (str::del_prefix($expr, "+")) {
        # config
        $mapKey = "$prefix+$expr";
        $expr = str_replace("'", "\\'", $expr);
        $expr = "_helper.config('$expr')";
      } elseif (str::del_prefix($expr, "*")) {
        # session
        $mapKey = "$prefix*$expr";
        $expr = str_replace("'", "\\'", $expr);
        $expr = "_helper.session('$expr')";
      } elseif (str::del_prefix($expr, ".")) {
        # session
        $mapKey = "$prefix.$expr";
        $expr = str_replace("'", "\\'", $expr);
        $expr = "_helper.value('$expr')";
      } elseif ($prefix !== null) {
        # sinon remettre le préfixe
        $expr = $orig;
      }

      if ($key === $index) {
        $index++;
        if ($mapKey !== false) {
          $exprs[$mapKey] = $expr;
        } else {
          # clé normale: la correspondance est en minuscule
          $exprs[$expr] = strtolower($expr);
        }
      } else {
        $exprs[$key] = $expr;
      }
    }
    uksort($exprs, function ($a, $b) {
      return -cv::complen($a, $b);
    });
    $this->exprs = $exprs;
  }

  /** @var ExpressionLanguage */
  protected $el;

  protected $subject;

  protected $body;

  protected $exprs;

  protected function _eval(string $template, ?array $data): string {
    if ($data === null) return $template;
    $el = $this->el;
    foreach ($this->exprs as $key => $expr) {
      $value = $el->evaluate($expr, $data);
      if (is_array($value)) $value = str::join(" ", $value);
      elseif (!is_string($value)) $value = strval($value);
      $template = str_replace($key, $value, $template);
    }
    return $template;
  }

  function eval(?array $data, $convertMd=true): array {
    if ($data !== null) {
      $data["_helper"] = new MailTemplateHelper($data);
    }
    $subject = $this->_eval($this->subject, $data);
    $body = $this->body;
    if ($convertMd) $body = mdc::convert($body);
    $body = $this->_eval($body, $data);
    return [
      "subject" => $subject,
      "body" => $body,
    ];
  }
}