/**
 * TypeScript errors near the cursor, as prompt context ("TS errors as context") and for verifying generated
 * training data. Shared by the training pipeline and the daemon so the format is identical in both.
 *
 * Rendered as a pseudo-file in the repo header:
 *   <|file_sep|>{dir}/__errors__.txt
 *   TS2304 Cannot find name 'getU'. | const user = getU
 */

export interface Diagnostic {
  /** 0-based line in the visible file. */
  line: number
  code: number
  message: string
  category: 'error' | 'warning'
}

/**
 * Errors that are noise for completion: environment problems (unresolved modules or types when dependencies
 * aren't installed) rather than mistakes in the code being written.
 */
export const IGNORED_CODES = new Set([
  2307, // Cannot find module
  7016, // Could not find a declaration file for module
  2792, // Cannot find module. Did you mean to set moduleResolution…
  7006, // Parameter implicitly has an 'any' type
  7031, // Binding element implicitly has an 'any' type
  2875, // JSX tag requires the module path … to exist
  6133, // declared but never read (unused), noise while writing
  6196, // declared but never used
])

export function relevantDiagnostics(diags: Diagnostic[], cursorLine: number, opts: { window?: number; max?: number } = {}): Diagnostic[] {
  const window = opts.window ?? 20
  const max = opts.max ?? 8
  return diags
    .filter(d => !IGNORED_CODES.has(d.code) && Math.abs(d.line - cursorLine) <= window)
    .sort((a, b) => Math.abs(a.line - cursorLine) - Math.abs(b.line - cursorLine) || a.line - b.line)
    .slice(0, max)
}

/** One line per diagnostic: code, message (first line), and the trimmed source line it points at. */
export function formatDiagnostics(diags: Diagnostic[], visible: string): string {
  const lines = visible.split('\n')
  return diags.map(d => {
    const message = d.message.split('\n')[0].slice(0, 160)
    const src = (lines[d.line] ?? '').trim().slice(0, 100)
    return `TS${d.code} ${message} | ${src}`
  }).join('\n')
}

/** Diagnostics present in `after` but not in `before`, matched by code + message (positions shift with edits). */
export function newDiagnostics(before: Diagnostic[], after: Diagnostic[]): Diagnostic[] {
  const counts = new Map<string, number>()
  for (const d of before) counts.set(`${d.code}:${d.message}`, (counts.get(`${d.code}:${d.message}`) ?? 0) + 1)
  const out: Diagnostic[] = []
  for (const d of after) {
    const key = `${d.code}:${d.message}`
    const n = counts.get(key) ?? 0
    if (n > 0) counts.set(key, n - 1)
    else if (!IGNORED_CODES.has(d.code)) out.push(d)
  }
  return out
}