// ─────────────────────────────────────────────
// GradeScope: Conversion Logic Architecture
// ─────────────────────────────────────────────

// 1. Normalize to percentage (0-100)
function normalizeToPercent(grade, country) {
  if (country.scale_type === 'percentage') {
    return grade; // already 0-100
  }
  if (country.grade_direction === 'desc') {
    // e.g. Germany 1.0=best, 4.0=pass, 5.0=fail
    return ((country.max_grade - grade) /
            (country.max_grade - country.min_grade)) * 100;
  }
  // linear ascending (e.g. Philippines 1.0=best handled separately)
  return ((grade - country.min_grade) /
          (country.max_grade - country.min_grade)) * 100;
}

// 2. Convert from percentage to destination scale
function fromPercentToScale(pct, country) {
  if (country.formula_type === 'bavarian') {
    return applyBavarianFormula(pct, country);
  }
  if (country.formula_type === 'classification') {
    return applyClassification(pct, country);
  }
  // linear default
  return country.min_grade +
    ((pct / 100) * (country.max_grade - country.min_grade));
}

// 3. Modified Bavarian Formula (Germany only)
// Formula: Xd = 1 + 3 × ((Nmax − Nd) / (Nmax − Nmin))
// Xd = German grade | Nd = input grade | Nmax = source max | Nmin = source passing
function applyBavarianFormula(inputGrade, srcCountry) {
  const Nd   = inputGrade;
  const Nmax = srcCountry.max_grade;
  const Nmin = srcCountry.passing_grade;
  const Xd   = 1 + 3 * ((Nmax - Nd) / (Nmax - Nmin));
  return Math.min(4.0, Math.max(1.0, Math.round(Xd * 10) / 10));
}

// 4. Classification mapping (UK / Ireland)
function applyClassification(pct, country) {
  const classes = country.grade_classifications;
  return classes.find(c => pct >= c.min_percent && pct <= c.max_percent)
    || classes[classes.length - 1];
}

// 5. Main entry point
function convertGrade(grade, srcCountry, dstCountry) {
  const pct    = normalizeToPercent(grade, srcCountry);
  const result = fromPercentToScale(pct, dstCountry);
  return { result, pct, formula: dstCountry.formula_type };
}

gradescope/
├── frontend/
│   ├── public/
│   │   ├── index.html
│   │   └── assets/
│   ├── src/
│   │   ├── pages/
│   │   │   ├── Home.jsx
│   │   │   ├── tools/
│   │   │   │   ├── GradeConverter.jsx
│   │   │   │   └── index.jsx          ← tools directory
│   │   │   └── blog/
│   │   │       ├── index.jsx          ← country grid
│   │   │       └── [country].jsx      ← dynamic country pages
│   │   ├── components/
│   │   │   ├── layout/
│   │   │   │   ├── Header.jsx
│   │   │   │   ├── Footer.jsx
│   │   │   │   └── NavDropdown.jsx
│   │   │   ├── converter/
│   │   │   │   ├── CountrySelect.jsx
│   │   │   │   ├── GradeInput.jsx
│   │   │   │   ├── ResultDisplay.jsx
│   │   │   │   ├── FormulaBlock.jsx
│   │   │   │   ├── StepByStep.jsx
│   │   │   │   └── ScaleTable.jsx
│   │   │   └── blog/
│   │   │       ├── CountryCard.jsx
│   │   │       └── CountryPage.jsx
│   │   ├── lib/
│   │   │   ├── conversion/
│   │   │   │   ├── index.js           ← main entry
│   │   │   │   ├── linear.js
│   │   │   │   ├── bavarian.js        ← Germany only
│   │   │   │   └── classification.js  ← UK/Ireland
│   │   │   └── countries/
│   │   │       ├── database.js        ← all 29 countries
│   │   │       └── scales/
│   │   │           ├── argentina.js
│   │   │           ├── germany.js     ← Bavarian config
│   │   │           ├── uk.js          ← classification config
│   │   │           └── ...            ← one file per country
├── backend/                           ← API (Node/FastAPI)
│   ├── routes/
│   │   ├── convert.js
│   │   └── countries.js
│   ├── services/
│   │   └── conversionEngine.js
│   └── db/
│       └── migrations/
├── content/
│   └── countries/                     ← MDX blog content
│       ├── argentina.mdx
│       ├── germany.mdx
│       └── ...                        ← one per country
└── README.md

// ─────────────────────────────────────────────
// GradeScope: Frontend Architecture Notes
// ─────────────────────────────────────────────

// Framework: Next.js (App Router) + Tailwind CSS
// Blog: MDX with gray-matter frontmatter
// Forms: React Hook Form + Zod validation
// SEO: next/metadata per page

// Route structure:
/                        → Home page
/tools                   → Tools index
/tools/grade-converter   → Conversion tool
/tools/gpa-calculator    → (future)
/blog                    → Country grid
/blog/[country]          → Dynamic country page

// SEO metadata per country page:
export const metadata = {
  title: `${country} Grading System Explained | GradeScope`,
  description: `Grade scale, degree structure, passing marks,
    and conversion guide for ${country}.`,
  keywords: [country, 'grading system', 'grade conversion',
             'academic equivalency'],
  openGraph: { type: 'article', ... }
}

// Country page structured data (JSON-LD):
{
  "@type": "Article",
  "name": "Germany Grading System",
  "about": { "@type": "Country", "name": "Germany" }
}