import { describe, it, expect } from 'vitest'
import { chromaAt, pcAt } from './fretboard'
import { triadNotes, diatonicChords, scaleNotes, intervalTarget } from './theory'
import { triadShape, STRING_SETS } from './triads'
import { cagedShapes } from './caged'
import { deriveRoles } from '../../drills'

describe('fretboard mapping', () => {
  it('maps open strings and frets correctly (index 0 = high e)', () => {
    expect(pcAt(0, 0)).toBe('E') // high e open
    expect(pcAt(5, 0)).toBe('E') // low E open
    expect(pcAt(5, 3)).toBe('G') // low E, 3rd fret
    expect(pcAt(4, 2)).toBe('B') // A string, 2nd fret
    expect(chromaAt(0, 0)).toBe(4) // E
  })
})

describe('theory helpers', () => {
  it('builds triads and diatonic chords', () => {
    expect(triadNotes('C', 'major')).toEqual(['C', 'E', 'G'])
    expect(triadNotes('A', 'minor')).toEqual(['A', 'C', 'E'])
    expect(diatonicChords('G').map((c) => c.name)).toEqual([
      'G', 'Am', 'Bm', 'C', 'D', 'Em', 'F#dim',
    ])
    expect(scaleNotes('G', 'dorian')).toEqual(['G', 'A', 'Bb', 'C', 'D', 'E', 'F'])
    expect(intervalTarget('A', '5P')).toBe('E')
  })
})

describe('deriveRoles', () => {
  it('accents, downbeats, and subdivisions land correctly', () => {
    // 4/4 sixteenths, accent on beat 1.
    const roles = deriveRoles(16, 4, [0])
    expect(roles[0]).toBe('accent')
    expect(roles[4]).toBe('normal') // beat 2 downbeat
    expect(roles[1]).toBe('subdivision')
  })
})

describe('triad inversions', () => {
  it('produces C major tones on the 1-2-3 string set', () => {
    const set = STRING_SETS.find((s) => s.id === '123')!
    for (const inv of ['root', '1st', '2nd']) {
      const shape = triadShape('C', 'major', set, inv)
      const chromas = shape.frets
        .map((f, string) => (f >= 0 ? chromaAt(string, f) : null))
        .filter((c): c is number => c !== null)
        .sort((a, b) => a - b)
      // C(0) E(4) G(7)
      expect(chromas).toEqual([0, 4, 7])
    }
  })
})

describe('CAGED shapes', () => {
  it('returns 5 shapes with the E-shape barre at fret 3 for key G', () => {
    const shapes = cagedShapes('G')
    expect(shapes).toHaveLength(5)
    const eShape = shapes.find((s) => s.form === 'E shape')!
    expect(eShape.barreFret).toBe(3)
    // Every marked position should be a chord tone of G major (G B D).
    const gTones = new Set([7, 11, 2])
    for (const p of shapes[0].positions) {
      expect(gTones.has(chromaAt(p.string, p.fret))).toBe(true)
    }
  })
})