import { describe, it, expect } from 'vitest'
import fc from 'fast-check'
import {
  formatTimestamp,
  getArrowClass,
  truncateMethod,
  needsTruncation,
} from '../../../inertia/helpers/sequence_viewer_helpers.js'

/**
 * Property 9: Arrow Direction Correctness
 * Validates: Requirements 4.2
 *
 * For any list of CWMP messages with mixed directions, the SequenceViewer SHALL render
 * each message arrow pointing left-to-right for "CPE→ACS" and right-to-left for "ACS→CPE",
 * with the overall list ordered by timestamp ascending.
 *
 * Since this is a component data logic test, we test the pure logic:
 * - Direction → CSS class mapping
 * - Timestamp ordering of the messages array
 */

const PBT_NUM_RUNS = 100

// --- Types (matching SequenceViewer.vue CwmpExchange interface) ---

interface CwmpExchange {
  sequenceNumber: number
  timestamp: string
  direction: 'CPE→ACS' | 'ACS→CPE'
  cwmpMethod: string
  sessionId: string
  rawXml: string
}

// --- Pure logic functions ---

/**
 * Checks if an array of messages is ordered by timestamp ascending.
 * The SequenceViewer displays messages in array order, and the API returns them
 * ordered by timestamp ascending.
 */
function isTimestampAscending(messages: CwmpExchange[]): boolean {
  for (let i = 1; i < messages.length; i++) {
    if (messages[i].timestamp < messages[i - 1].timestamp) {
      return false
    }
  }
  return true
}

// --- Arbitraries ---

/**
 * Generates a random direction value.
 */
const arbDirection = fc.constantFrom<'CPE→ACS' | 'ACS→CPE'>('CPE→ACS', 'ACS→CPE')

/**
 * Generates a random ISO 8601 timestamp within a reasonable range.
 */
const arbTimestamp = fc
  .integer({
    min: new Date('2024-01-01T00:00:00.000Z').getTime(),
    max: new Date('2025-12-31T23:59:59.999Z').getTime(),
  })
  .map((ms) => new Date(ms).toISOString())

/**
 * Generates a random CWMP method name.
 */
const arbCwmpMethod = fc.constantFrom(
  'Inform',
  'GetParameterValues',
  'GetParameterValuesResponse',
  'SetParameterValues',
  'SetParameterValuesResponse',
  'AddObject',
  'AddObjectResponse',
  'DeleteObject',
  'DeleteObjectResponse',
  'Download',
  'DownloadResponse',
  'Reboot',
  'RebootResponse',
  'FactoryReset',
  'Fault',
  'Empty',
  'Unknown'
)

/**
 * Generates a single CwmpExchange with the given sequence number and a sorted-friendly timestamp.
 */
function arbExchange(seqNum: number): fc.Arbitrary<CwmpExchange> {
  return fc
    .record({
      timestamp: arbTimestamp,
      direction: arbDirection,
      cwmpMethod: arbCwmpMethod,
      sessionId: fc.string({ minLength: 5, maxLength: 30 }),
      rawXml: fc.string({ minLength: 0, maxLength: 100 }),
    })
    .map(({ timestamp, direction, cwmpMethod, sessionId, rawXml }) => ({
      sequenceNumber: seqNum,
      timestamp,
      direction,
      cwmpMethod,
      sessionId,
      rawXml,
    }))
}

/**
 * Generates a list of CwmpExchange messages sorted by timestamp ascending
 * (simulating what the API returns and how SequenceViewer receives them).
 */
const arbSortedExchangeList = fc
  .array(
    fc.record({
      timestamp: arbTimestamp,
      direction: arbDirection,
      cwmpMethod: arbCwmpMethod,
      sessionId: fc.string({ minLength: 5, maxLength: 30 }),
      rawXml: fc.string({ minLength: 0, maxLength: 100 }),
    }),
    { minLength: 1, maxLength: 50 }
  )
  .map((items) => {
    // Sort by timestamp ascending to simulate API-ordered data
    items.sort((a, b) => a.timestamp.localeCompare(b.timestamp))
    return items.map((item, index) => ({
      ...item,
      sequenceNumber: index + 1,
    }))
  })

/**
 * Generates a list with ALL messages having the same direction.
 */
function arbUniformDirectionList(direction: 'CPE→ACS' | 'ACS→CPE') {
  return fc
    .array(
      fc.record({
        timestamp: arbTimestamp,
        cwmpMethod: arbCwmpMethod,
        sessionId: fc.string({ minLength: 5, maxLength: 30 }),
        rawXml: fc.string({ minLength: 0, maxLength: 100 }),
      }),
      { minLength: 1, maxLength: 30 }
    )
    .map((items) => {
      items.sort((a, b) => a.timestamp.localeCompare(b.timestamp))
      return items.map((item, index) => ({
        ...item,
        direction,
        sequenceNumber: index + 1,
      }))
    })
}

// --- Property Tests ---

describe('Property 9: Arrow Direction Correctness', () => {
  it('CPE→ACS messages always get "arrow-right" class (left-to-right arrow)', () => {
    fc.assert(
      fc.property(arbSortedExchangeList, (messages) => {
        for (const message of messages) {
          if (message.direction === 'CPE→ACS') {
            expect(getArrowClass(message.direction)).toBe('arrow-right')
          }
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('ACS→CPE messages always get "arrow-left" class (right-to-left arrow)', () => {
    fc.assert(
      fc.property(arbSortedExchangeList, (messages) => {
        for (const message of messages) {
          if (message.direction === 'ACS→CPE') {
            expect(getArrowClass(message.direction)).toBe('arrow-left')
          }
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('arrow class is exclusively determined by direction — no other field affects it', () => {
    fc.assert(
      fc.property(arbSortedExchangeList, (messages) => {
        for (const message of messages) {
          const arrowClass = getArrowClass(message.direction)
          // The arrow class is a bijection: exactly two valid outputs
          expect(['arrow-right', 'arrow-left']).toContain(arrowClass)
          // And each direction maps to exactly one class
          if (message.direction === 'CPE→ACS') {
            expect(arrowClass).toBe('arrow-right')
          } else {
            expect(arrowClass).toBe('arrow-left')
          }
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('messages with mixed directions are displayed in timestamp-ascending order', () => {
    fc.assert(
      fc.property(arbSortedExchangeList, (messages) => {
        // The API-sorted list must be in timestamp ascending order
        expect(isTimestampAscending(messages)).toBe(true)

        // Each message still gets the correct arrow class regardless of position
        for (const message of messages) {
          const expectedClass =
            message.direction === 'CPE→ACS' ? 'arrow-right' : 'arrow-left'
          expect(getArrowClass(message.direction)).toBe(expectedClass)
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('all-CPE→ACS lists: every arrow is "arrow-right" and order is maintained', () => {
    fc.assert(
      fc.property(arbUniformDirectionList('CPE→ACS'), (messages) => {
        expect(isTimestampAscending(messages)).toBe(true)
        for (const message of messages) {
          expect(getArrowClass(message.direction)).toBe('arrow-right')
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('all-ACS→CPE lists: every arrow is "arrow-left" and order is maintained', () => {
    fc.assert(
      fc.property(arbUniformDirectionList('ACS→CPE'), (messages) => {
        expect(isTimestampAscending(messages)).toBe(true)
        for (const message of messages) {
          expect(getArrowClass(message.direction)).toBe('arrow-left')
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('single message: correct arrow class regardless of direction', () => {
    fc.assert(
      fc.property(arbDirection, arbTimestamp, (direction, timestamp) => {
        const message: CwmpExchange = {
          sequenceNumber: 1,
          timestamp,
          direction,
          cwmpMethod: 'Inform',
          sessionId: 'test-session',
          rawXml: '<xml/>',
        }
        const expectedClass =
          direction === 'CPE→ACS' ? 'arrow-right' : 'arrow-left'
        expect(getArrowClass(message.direction)).toBe(expectedClass)
        // Single-element list is trivially sorted
        expect(isTimestampAscending([message])).toBe(true)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('alternating directions preserve timestamp order and correct arrow assignment', () => {
    // Generate an alternating direction list
    const arbAlternatingList = fc
      .array(arbTimestamp, { minLength: 2, maxLength: 40 })
      .map((timestamps) => {
        const sorted = [...timestamps].sort()
        return sorted.map((ts, i) => ({
          sequenceNumber: i + 1,
          timestamp: ts,
          direction: (i % 2 === 0 ? 'CPE→ACS' : 'ACS→CPE') as 'CPE→ACS' | 'ACS→CPE',
          cwmpMethod: 'Inform',
          sessionId: 'session-alt',
          rawXml: '',
        }))
      })

    fc.assert(
      fc.property(arbAlternatingList, (messages) => {
        expect(isTimestampAscending(messages)).toBe(true)
        for (let i = 0; i < messages.length; i++) {
          const msg = messages[i]
          if (i % 2 === 0) {
            expect(msg.direction).toBe('CPE→ACS')
            expect(getArrowClass(msg.direction)).toBe('arrow-right')
          } else {
            expect(msg.direction).toBe('ACS→CPE')
            expect(getArrowClass(msg.direction)).toBe('arrow-left')
          }
        }
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })
})


/**
 * Property 10: Method Label Truncation
 * Validates: Requirements 4.3
 *
 * For any cwmpMethod name, if its length exceeds 40 characters, the displayed label
 * SHALL be truncated to 40 characters; if length ≤ 40, the full name SHALL be displayed.
 */
describe('Property 10: Method Label Truncation', () => {
  it('strings longer than 40 characters are truncated to exactly 40 chars plus ellipsis', () => {
    fc.assert(
      fc.property(
        fc.string({ minLength: 41, maxLength: 200 }),
        (method) => {
          const result = truncateMethod(method)
          // The visible portion (before ellipsis) must be exactly the first 40 chars of the original
          expect(result.substring(0, 40)).toBe(method.substring(0, 40))
          // The result ends with the ellipsis character
          expect(result.endsWith('…')).toBe(true)
          // Total length is 41 (40 chars + 1 ellipsis char '…')
          expect(result.length).toBe(41)
        }
      ),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('strings of 40 characters or fewer are displayed in full without truncation', () => {
    fc.assert(
      fc.property(
        fc.string({ minLength: 0, maxLength: 40 }),
        (method) => {
          const result = truncateMethod(method)
          // The full original string is returned unchanged
          expect(result).toBe(method)
          expect(result.length).toBe(method.length)
        }
      ),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('needsTruncation returns true if and only if method length exceeds 40', () => {
    fc.assert(
      fc.property(
        fc.string({ minLength: 0, maxLength: 200 }),
        (method) => {
          const result = needsTruncation(method)
          expect(result).toBe(method.length > 40)
        }
      ),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('truncation preserves the first 40 characters of the original string', () => {
    fc.assert(
      fc.property(
        fc.string({ minLength: 41, maxLength: 300 }),
        (method) => {
          const result = truncateMethod(method)
          // The truncated output starts with the first 40 chars of the input
          expect(result.substring(0, 40)).toBe(method.substring(0, 40))
        }
      ),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('exactly 40 characters are NOT truncated', () => {
    fc.assert(
      fc.property(
        fc.string({ minLength: 40, maxLength: 40 }),
        (method) => {
          const result = truncateMethod(method)
          expect(result).toBe(method)
          expect(result.length).toBe(40)
          expect(needsTruncation(method)).toBe(false)
        }
      ),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('exactly 41 characters ARE truncated', () => {
    fc.assert(
      fc.property(
        fc.string({ minLength: 41, maxLength: 41 }),
        (method) => {
          const result = truncateMethod(method)
          expect(result.length).toBe(41)
          expect(result.endsWith('…')).toBe(true)
          expect(needsTruncation(method)).toBe(true)
          // The first 40 chars match
          expect(result.substring(0, 40)).toBe(method.substring(0, 40))
        }
      ),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('empty string is not truncated', () => {
    const result = truncateMethod('')
    expect(result).toBe('')
    expect(needsTruncation('')).toBe(false)
  })

  it('unicode characters in method names respect character-length truncation', () => {
    // Generate strings with multi-byte unicode characters (BMP range)
    const unicodeMethodArb = fc
      .array(fc.integer({ min: 0x0100, max: 0xFFFF }), { minLength: 41, maxLength: 100 })
      .map((codePoints) => String.fromCharCode(...codePoints))

    fc.assert(
      fc.property(unicodeMethodArb, (method) => {
        const result = truncateMethod(method)
        // Truncation is based on JS string length (char count), not byte count
        expect(result.length).toBe(41)
        expect(result.endsWith('…')).toBe(true)
        expect(needsTruncation(method)).toBe(true)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })
})

/**
 * Property 11: Timestamp Formatting
 * Validates: Requirements 4.4
 *
 * For any valid ISO 8601 timestamp, the formatted display SHALL match the pattern
 * `HH:mm:ss.SSS` (hours:minutes:seconds.milliseconds).
 */
describe('Property 11: Timestamp Formatting', () => {
  // ─── Arbitraries ─────────────────────────────────────────────────────────────

  /**
   * Arbitrary that generates valid ISO 8601 timestamps as strings.
   * Uses integer milliseconds to avoid invalid Date issues.
   */
  const validIsoTimestamp = fc
    .integer({
      min: 0, // 1970-01-01T00:00:00.000Z
      max: 4102444799999, // 2099-12-31T23:59:59.999Z
    })
    .map((ms) => new Date(ms).toISOString())

  /**
   * Arbitrary that generates ISO 8601 timestamps with timezone offsets.
   * E.g., "2025-06-15T14:30:00.123+05:30"
   */
  const isoTimestampWithOffset = fc
    .record({
      ms: fc.integer({ min: 0, max: 4102444799999 }),
      offsetHours: fc.integer({ min: -12, max: 14 }),
      offsetMinutes: fc.constantFrom(0, 30, 45),
    })
    .map(({ ms, offsetHours, offsetMinutes }) => {
      const date = new Date(ms)
      const year = date.getUTCFullYear()
      const month = String(date.getUTCMonth() + 1).padStart(2, '0')
      const day = String(date.getUTCDate()).padStart(2, '0')
      const hours = String(date.getUTCHours()).padStart(2, '0')
      const minutes = String(date.getUTCMinutes()).padStart(2, '0')
      const seconds = String(date.getUTCSeconds()).padStart(2, '0')
      const millis = String(date.getUTCMilliseconds()).padStart(3, '0')

      const sign = offsetHours >= 0 ? '+' : '-'
      const absHours = String(Math.abs(offsetHours)).padStart(2, '0')
      const absMinutes = String(offsetMinutes).padStart(2, '0')

      return `${year}-${month}-${day}T${hours}:${minutes}:${seconds}.${millis}${sign}${absHours}:${absMinutes}`
    })

  // ─── Pattern regex ───────────────────────────────────────────────────────────

  const TIMESTAMP_PATTERN = /^\d{2}:\d{2}:\d{2}\.\d{3}$/

  // ─── Property Tests ──────────────────────────────────────────────────────────

  it('should format any valid ISO 8601 timestamp to HH:mm:ss.SSS pattern', () => {
    fc.assert(
      fc.property(validIsoTimestamp, (isoStr) => {
        const result = formatTimestamp(isoStr)
        expect(result).toMatch(TIMESTAMP_PATTERN)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('should produce correct UTC time components from ISO timestamp', () => {
    fc.assert(
      fc.property(validIsoTimestamp, (isoStr) => {
        const result = formatTimestamp(isoStr)
        const date = new Date(isoStr)

        const expectedHours = String(date.getUTCHours()).padStart(2, '0')
        const expectedMinutes = String(date.getUTCMinutes()).padStart(2, '0')
        const expectedSeconds = String(date.getUTCSeconds()).padStart(2, '0')
        const expectedMillis = String(date.getUTCMilliseconds()).padStart(3, '0')
        const expected = `${expectedHours}:${expectedMinutes}:${expectedSeconds}.${expectedMillis}`

        expect(result).toBe(expected)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('should format timestamps with timezone offsets to HH:mm:ss.SSS pattern', () => {
    fc.assert(
      fc.property(isoTimestampWithOffset, (isoStr) => {
        const result = formatTimestamp(isoStr)
        expect(result).toMatch(TIMESTAMP_PATTERN)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('should produce valid hour values (00-23)', () => {
    fc.assert(
      fc.property(validIsoTimestamp, (isoStr) => {
        const result = formatTimestamp(isoStr)
        const hours = parseInt(result.substring(0, 2), 10)
        expect(hours).toBeGreaterThanOrEqual(0)
        expect(hours).toBeLessThanOrEqual(23)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('should produce valid minute values (00-59)', () => {
    fc.assert(
      fc.property(validIsoTimestamp, (isoStr) => {
        const result = formatTimestamp(isoStr)
        const minutes = parseInt(result.substring(3, 5), 10)
        expect(minutes).toBeGreaterThanOrEqual(0)
        expect(minutes).toBeLessThanOrEqual(59)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('should produce valid second values (00-59)', () => {
    fc.assert(
      fc.property(validIsoTimestamp, (isoStr) => {
        const result = formatTimestamp(isoStr)
        const seconds = parseInt(result.substring(6, 8), 10)
        expect(seconds).toBeGreaterThanOrEqual(0)
        expect(seconds).toBeLessThanOrEqual(59)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  it('should produce valid millisecond values (000-999)', () => {
    fc.assert(
      fc.property(validIsoTimestamp, (isoStr) => {
        const result = formatTimestamp(isoStr)
        const millis = parseInt(result.substring(9, 12), 10)
        expect(millis).toBeGreaterThanOrEqual(0)
        expect(millis).toBeLessThanOrEqual(999)
      }),
      { numRuns: PBT_NUM_RUNS }
    )
  })

  // ─── Edge cases ──────────────────────────────────────────────────────────────

  it('should format midnight correctly', () => {
    const result = formatTimestamp('2025-01-01T00:00:00.000Z')
    expect(result).toBe('00:00:00.000')
  })

  it('should format noon correctly', () => {
    const result = formatTimestamp('2025-01-01T12:00:00.000Z')
    expect(result).toBe('12:00:00.000')
  })

  it('should format end-of-day correctly', () => {
    const result = formatTimestamp('2025-01-01T23:59:59.999Z')
    expect(result).toBe('23:59:59.999')
  })

  it('should handle millisecond precision correctly', () => {
    const result = formatTimestamp('2025-06-15T10:30:00.001Z')
    expect(result).toBe('10:30:00.001')
  })

  it('should handle zero milliseconds correctly', () => {
    const result = formatTimestamp('2025-06-15T10:30:45.000Z')
    expect(result).toBe('10:30:45.000')
  })
})