namespace RealCV.Application.Data;

/// <summary>
/// Institutions not recognised by UK higher education regulatory bodies.
/// Sources: HEDD, Oregon ODA, UNESCO warnings, Michigan AG list
/// </summary>
public static class UnaccreditedInstitutions
{
    /// <summary>
    /// Institutions identified by regulatory bodies as not meeting recognised accreditation standards.
    /// This list includes institutions flagged by various educational oversight organisations.
    /// </summary>
    public static readonly HashSet<string> KnownUnaccredited = new(StringComparer.OrdinalIgnoreCase)
    {
        // Institutions not meeting accreditation standards
        "Almeda University",
        "Ashwood University",
        "Belford University",
        "Bircham University",
        "Breyer State University",
        "Brighton University (not Brighton UK)",
        "Buxton University",
        "Cambridge State University",
        "Chadwick University",
        "Clayton University",
        "Columbus University",
        "Corllins University",
        "Dartington University",
        "Dickinson State University Online",
        "Fairfax University",
        "Glendale University",
        "Greenleaf University",
        "Hamilton University",
        "Harrington University",
        "Hill University",
        "Hollywood University",
        "International University (generic)",
        "Irish International University",
        "James Monroe University",
        "Jamestown University",
        "Kennedy-Western University",
        "Kensington University",
        "Knightsbridge University",
        "LaSalle University (Louisiana)",
        "Lexington University",
        "Lincoln University (if not Pennsylvania)",
        "Madison University",
        "Metropolitan University (generic)",
        "Middletown University",
        "Monticello University",
        "Northern University",
        "Northfield University",
        "Pacific Southern University",
        "Pacific Western University",
        "Paramount University",
        "Parkwood University",
        "Preston University",
        "Redding University",
        "Richmond University (not American Intl)",
        "Robertstown University",
        "Rochdale University",
        "Rochville University",
        "Saint Regis University",
        "St Regis University",
        "Shaftesbury University",
        "Shelbourne University",
        "Stanton University",
        "Stratford University (if unaccredited)",
        "Suffield University",
        "Summit University (unaccredited)",
        "Sussex College of Technology",
        "Trinity College and University",
        "Trinity Southern University",
        "University Degree Program",
        "University of Atlanta",
        "University of Berkley",
        "University of Devonshire",
        "University of Dunham",
        "University of England",
        "University of Northern Washington",
        "University of Palmers Green",
        "University of San Moritz",
        "University of Sussex (not the legitimate University of Sussex)",
        "University of Wexford",
        "Vocational University",
        "Warnborough University",
        "Washington International University",
        "Weston Reserve University",
        "Westbourne University",
        "Western States University",
        "Woodfield University",
        "Yorker International University",

        // Unaccredited institutions commonly seen in UK applications
        "Axact University",
        "Brooklyn Park University",
        "Columbiana University",
        "Hillford University",
        "Nixon University",
        "Oxbridge University",
        "University of Newford",

        // Online unaccredited institutions
        "American World University",
        "Ashford University (pre-2005)",
        "Concordia College and University",
        "Columbus State University (unaccredited variant)",
        "Frederick Taylor University",
        "International Theological University",
        "Nations University",
        "Paramount California University",
        "University of Ancient Studies",
        "University of Asia",
        "Virtual University (unaccredited)",
    };

    /// <summary>
    /// Patterns in institution names that may indicate unaccredited status.
    /// </summary>
    public static readonly string[] SuspiciousPatterns =
    [
        "online university",
        "virtual university",
        "life experience",
        "no classes required",
        "degree in days",
        "accredited by",      // followed by fake accreditor
        "internationally recognised",
        "worldwide university",
        "global university",
        "premier university",
        "elite university",
        "executive university",
        "professional university",
        "distance learning university", // be careful - some are legit
    ];

    /// <summary>
    /// Check if an institution is not recognised by accreditation bodies.
    /// </summary>
    public static bool IsUnaccredited(string institutionName)
    {
        if (string.IsNullOrWhiteSpace(institutionName))
            return false;

        var normalised = institutionName.Trim();

        // Direct match
        if (KnownUnaccredited.Contains(normalised))
            return true;

        // Check if name contains known unaccredited institution
        foreach (var institution in KnownUnaccredited)
        {
            if (normalised.Contains(institution, StringComparison.OrdinalIgnoreCase))
                return true;
        }

        return false;
    }

    /// <summary>
    /// Check if institution name has patterns that may indicate unaccredited status.
    /// Returns true if patterns suggest further verification is recommended.
    /// </summary>
    public static bool HasSuspiciousPattern(string institutionName)
    {
        if (string.IsNullOrWhiteSpace(institutionName))
            return false;

        var lower = institutionName.ToLowerInvariant();

        foreach (var pattern in SuspiciousPatterns)
        {
            if (lower.Contains(pattern))
                return true;
        }

        return false;
    }
}