using JobTrackerApi.Models;

namespace JobTrackerApi.Services;

// Phase 3 (validation): guards against abuse/DoS on the career-profile write path, NOT content
// completeness (that is CareerCompleteness's job — a WIP profile must always be savable). Enforces
// item counts and string lengths so a single PUT cannot store an unbounded blob. Returns an error
// string to reject, or null to accept.
public static class CareerProfileValidator
{
    private const int MaxItemsPerSection = 200;   // generous; a real CV has < 50
    private const int MaxListEntries = 200;        // bullets/skills/details per item
    private const int MaxShortField = 500;         // titles, names, single-line fields
    private const int MaxLongField = 5000;         // a single bullet/summary line

    public static string? Validate(StructuredCvProfile p)
    {
        if (p.Jobs.Count > MaxItemsPerSection) return $"Too many experience entries (max {MaxItemsPerSection}).";
        if (p.Education.Count > MaxItemsPerSection) return $"Too many education entries (max {MaxItemsPerSection}).";
        if (p.Skills.Count > MaxItemsPerSection) return $"Too many skills (max {MaxItemsPerSection}).";
        if (p.Projects.Count > MaxItemsPerSection) return $"Too many projects (max {MaxItemsPerSection}).";
        if (p.Certifications.Count > MaxItemsPerSection) return $"Too many certifications (max {MaxItemsPerSection}).";
        if (p.Languages.Count > MaxItemsPerSection) return $"Too many languages (max {MaxItemsPerSection}).";
        if (p.Summary.Count > MaxListEntries) return $"Summary is too long (max {MaxListEntries} lines).";

        foreach (var j in p.Jobs)
        {
            if (Over(j.Id, MaxShortField) || Over(j.Title, MaxShortField) || Over(j.Company, MaxShortField)
                || Over(j.Location, MaxShortField) || Over(j.Start, MaxShortField) || Over(j.End, MaxShortField))
                return "An experience field exceeds the allowed length.";
            if (j.Bullets.Count > MaxListEntries || j.Skills.Count > MaxListEntries) return "An experience has too many bullets/skills.";
            if (j.Bullets.Any(b => Over(b, MaxLongField)) || j.Skills.Any(s => Over(s, MaxShortField))) return "An experience bullet or skill is too long.";
        }
        foreach (var e in p.Education)
        {
            if (Over(e.Id, MaxShortField) || Over(e.Qualification, MaxShortField) || Over(e.QualificationLevel, MaxShortField)
                || Over(e.Institution, MaxShortField) || Over(e.Location, MaxShortField)
                || Over(e.Start, MaxShortField) || Over(e.End, MaxShortField)) return "An education field exceeds the allowed length.";
            if (e.Details.Count > MaxListEntries) return "An education entry has too many details.";
            if (e.Details.Any(detail => Over(detail, MaxLongField))) return "An education detail is too long.";
        }
        foreach (var pr in p.Projects)
        {
            if (Over(pr.Id, MaxShortField) || Over(pr.Name, MaxShortField) || Over(pr.Role, MaxShortField)
                || Over(pr.Location, MaxShortField) || Over(pr.Start, MaxShortField) || Over(pr.End, MaxShortField)) return "A project field exceeds the allowed length.";
            if (pr.Bullets.Count > MaxListEntries || pr.Skills.Count > MaxListEntries) return "A project has too many bullets/skills.";
            if (pr.Bullets.Any(bullet => Over(bullet, MaxLongField)) || pr.Skills.Any(skill => Over(skill, MaxShortField))) return "A project bullet or skill is too long.";
        }
        foreach (var certification in p.Certifications)
        {
            if (Over(certification.Id, MaxShortField) || Over(certification.Name, MaxShortField)
                || Over(certification.Issuer, MaxShortField) || Over(certification.Location, MaxShortField)
                || Over(certification.Date, MaxShortField)) return "A certification field exceeds the allowed length.";
            if (certification.Details.Count > MaxListEntries) return "A certification has too many details.";
            if (certification.Details.Any(detail => Over(detail, MaxLongField))) return "A certification detail is too long.";
        }
        foreach (var language in p.Languages)
        {
            if (Over(language.Name, MaxShortField) || Over(language.Level, MaxShortField) || Over(language.Notes, MaxLongField))
                return "A language field exceeds the allowed length.";
        }
        foreach (var s in p.Skills)
            if (Over(s, MaxShortField)) return "A skill entry is too long.";

        if (Over(p.Contact.FullName, MaxShortField) || Over(p.Contact.Email, MaxShortField)
            || Over(p.Contact.Headline, MaxShortField) || Over(p.Contact.Phone, MaxShortField)
            || Over(p.Contact.Location, MaxShortField) || Over(p.Contact.Website, MaxShortField)
            || Over(p.Contact.LinkedIn, MaxShortField))
            return "A contact field exceeds the allowed length.";

        return null;
    }

    private static bool Over(string? value, int max) => value is not null && value.Length > max;
}