jobtrackingapp/JobTrackerApi/Services/GmailParsing.cs

namespace JobTrackerApi.Services;

// Pure parsing/formatting helpers used by GmailController, split out for readability (no
// behaviour change). All are static and side-effect free.
public static class GmailParsing
{
    public static string ApplySyncBoundary(string query, int lookbackDays, bool includeSpamTrash)
    {
        var bounded = (query ?? string.Empty).Trim();
        if (!bounded.Contains("newer_than:", StringComparison.OrdinalIgnoreCase))
        {
            bounded = string.IsNullOrWhiteSpace(bounded)
                ? $"newer_than:{lookbackDays}d"
                : $"{bounded} newer_than:{lookbackDays}d";
        }

        if (!includeSpamTrash)
        {
            if (!bounded.Contains("in:spam", StringComparison.OrdinalIgnoreCase)) bounded += " -in:spam";
            if (!bounded.Contains("in:trash", StringComparison.OrdinalIgnoreCase)) bounded += " -in:trash";
        }

        return bounded.Trim();
    }

    public static bool LooksLikeJobRelatedThread(IReadOnlyList<GmailQueryMatchedMessage> orderedMessages)
    {
        var sample = string.Join("\n", orderedMessages.Select(item => string.Join(" ", new[] { item.Message.Subject, item.Message.From, item.Message.Snippet }.Where(value => !string.IsNullOrWhiteSpace(value)))));
        if (string.IsNullOrWhiteSpace(sample)) return false;
        return sample.Contains("interview", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("application", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("recruit", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("role", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("position", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("offer", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("follow up", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("follow-up", StringComparison.OrdinalIgnoreCase)
            || sample.Contains("rejection", StringComparison.OrdinalIgnoreCase);
    }

    public static string ToConfidence(int score)
    {
        return score switch
        {
            >= 30 => "high",
            >= 16 => "medium",
            _ => "low"
        };
    }

    public static string? ExtractFirstEmail(string? value)
    {
        if (string.IsNullOrWhiteSpace(value)) return null;
        var match = System.Text.RegularExpressions.Regex.Match(value, @"[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
        return match.Success ? match.Value : null;
    }

    public static string? ExtractRecruiterName(string? value)
    {
        if (string.IsNullOrWhiteSpace(value)) return null;
        var trimmed = value.Split('<')[0].Trim().Trim('"');
        return string.IsNullOrWhiteSpace(trimmed) || trimmed.Contains('@') ? null : trimmed;
    }

    public static string? ExtractCompanyName(string? from, string? subject)
    {
        var subjectText = (subject ?? string.Empty).Trim();
        if (!string.IsNullOrWhiteSpace(subjectText))
        {
            var parts = subjectText.Split(new[] { '-', '–', '|' }, StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
            if (parts.Length >= 2) return parts[0];
        }

        var recruiterName = ExtractRecruiterName(from);
        return recruiterName is { Length: > 0 } && recruiterName.Contains(' ') ? recruiterName.Split(' ').Last() : null;
    }

    public static string? ExtractRoleFromSubject(string? subject)
    {
        if (string.IsNullOrWhiteSpace(subject)) return null;
        var trimmed = subject.Trim();
        if (trimmed.Contains("interview", StringComparison.OrdinalIgnoreCase))
        {
            return trimmed.Replace("interview", string.Empty, StringComparison.OrdinalIgnoreCase).Trim(' ', '-', ':');
        }
        return trimmed.Length <= 120 ? trimmed : trimmed[..120];
    }

    public static string BuildPopupHtml(bool success, string message)
    {
        var escaped = System.Net.WebUtility.HtmlEncode(message);
        var status = success ? "connected" : "error";
        var title = success ? "Gmail connected" : "Gmail connection failed";
        var serializedMessage = System.Text.Json.JsonSerializer.Serialize(message);
        return $@"<!doctype html>
<html>
<head>
  <meta charset=""utf-8"" />
  <title>Gmail connection</title>
</head>
<body style=""font-family:Segoe UI,Arial,sans-serif;padding:24px;line-height:1.5;"">
  <h2>{title}</h2>
  <p>{escaped}</p>
  <p>You can close this window.</p>
  <script>
    if (window.opener) {{
      window.opener.postMessage({{ source: 'jobtracker-gmail-oauth', status: '{status}', message: {serializedMessage} }}, '*');
    }}
    window.close();
  </script>
</body>
</html>";
    }
}