export interface ConvergenceInspection {
  status: string;
  color: string;
  note: string;
  hasWarning: boolean;
}

export interface EngineIssueTarget {
  type: 'node' | 'link';
  id: string;
}

export interface EngineIssue {
  message: string;
  severity: 'error' | 'warning';
  target: EngineIssueTarget | null;
}

const ENGINE_ISSUE_LINE_PATTERN =
  /WARNING|Error\s+\d+|disconnected|unbalanced|cannot deliver|negative pressure/i;

/**
 * Extracts individual warning/error lines from an EPANET .rpt report body and
 * links each one to the specific node/link it concerns, when identifiable --
 * so "왜 실패했는지" doesn't require manually reading the raw report text and
 * cross-referencing IDs by hand. Rather than trying to match every phrasing
 * EPANET might use for a message ("Node %s disconnected", "Pump %s shut
 * down", etc, which vary across engine versions), this scans each flagged
 * line's own tokens against the model's actual node/link IDs -- so it finds
 * the referenced object regardless of the surrounding sentence, at the cost
 * of occasionally missing a reference that isn't a whole token (rare in
 * EPANET's report format, which always writes IDs as standalone words).
 */
export function extractEngineIssues(
  reportText: string | undefined | null,
  nodeIds: Iterable<string>,
  linkIds: Iterable<string>
): EngineIssue[] {
  if (!reportText) return [];
  const nodeIdSet = new Set(nodeIds);
  const linkIdSet = new Set(linkIds);
  if (nodeIdSet.size === 0 && linkIdSet.size === 0) return [];

  const issues: EngineIssue[] = [];
  for (const rawLine of reportText.split(/\r?\n/)) {
    const line = rawLine.trim();
    if (!line || !ENGINE_ISSUE_LINE_PATTERN.test(line)) continue;

    let target: EngineIssueTarget | null = null;
    for (const token of line.split(/[\s,;:()]+/)) {
      if (!token) continue;
      if (nodeIdSet.has(token)) {
        target = { type: 'node', id: token };
        break;
      }
      if (linkIdSet.has(token)) {
        target = { type: 'link', id: token };
        break;
      }
    }

    issues.push({
      message: line,
      severity: /Error\s+\d+/i.test(line) ? 'error' : 'warning',
      target,
    });
  }
  return issues;
}

export interface EngineWarning {
  time: number;
  code: number;
}

// EPANET warning codes returned by EN_runH (src/errors.dat, "WARNING" block).
const WARNING_TEXT: Record<number, string> = {
  1: 'System hydraulically unbalanced (수리방정식 미수렴)',
  2: 'Pumps cannot deliver head or flow (펌프 양정/유량 부족)',
  3: 'Valves cannot deliver flow or pressure (밸브 제어 불가)',
  4: 'Pumps/valves cannot deliver (펌프·밸브 제어 불가)',
  5: 'Network disconnected (관망 단절)',
  6: 'Negative pressures (음압 발생)',
};

// Pressures this far from any real network (in psi, m, kPa, bar or ft) only
// come out of a singular/disconnected solve, never from a physical answer.
const IMPLAUSIBLE_PRESSURE = 1e5;

function formatClock(seconds: number): string {
  const h = Math.floor(seconds / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  return `${h}:${String(m).padStart(2, '0')}`;
}

/**
 * Turns warning codes collected directly from the engine (not from the report
 * text, which loses them under "[REPORT] MESSAGES NO") into report-style lines.
 */
export function engineWarningLines(warnings: EngineWarning[] | undefined | null): string[] {
  if (!warnings || warnings.length === 0) return [];
  return warnings.map((w) => `WARNING ${w.code}: ${WARNING_TEXT[w.code] ?? 'Engine warning'} at ${formatClock(w.time)} hrs.`);
}

export function findImplausiblePressureNodes(
  nodes: Record<string, { type?: number; timeSeries?: { pressure?: number[] }; pressure?: number }> | undefined
): string[] {
  if (!nodes) return [];
  const ids: string[] = [];
  for (const [id, node] of Object.entries(nodes)) {
    const series = node.timeSeries?.pressure ?? [node.pressure ?? 0];
    if (series.some((p) => Math.abs(p) > IMPLAUSIBLE_PRESSURE)) ids.push(id);
  }
  return ids;
}

/**
 * Verdict for a whole simulation result: the report text, plus the warning
 * codes the engine returned directly, plus a physical-plausibility check on
 * pressures. Prefer this over inspectConvergence whenever a result is at hand.
 */
export function inspectSimulation(
  result: {
    reportText?: string;
    engineWarnings?: EngineWarning[];
    nodes?: Record<string, { type?: number; timeSeries?: { pressure?: number[] }; pressure?: number }>;
  } | null | undefined
): ConvergenceInspection {
  if (!result) return inspectConvergence(null);
  const base = inspectConvergence(result.reportText);
  if (base.hasWarning) return base;
  const warningLines = engineWarningLines(result.engineWarnings);
  const implausible = findImplausiblePressureNodes(result.nodes);
  if (warningLines.length > 0 || implausible.length > 0) {
    const parts: string[] = [];
    if (warningLines.length > 0) parts.push(`엔진 경고 ${warningLines.length}건 (보고서에는 기록되지 않음)`);
    if (implausible.length > 0) parts.push(`비물리적 압력 절점 ${implausible.length}개 (${implausible.slice(0, 5).join(', ')}${implausible.length > 5 ? ' 외' : ''})`);
    return {
      status: '경고/불균형 발생 (엔진 로그 확인 필요)',
      color: '#dc2626',
      note: parts.join(' · '),
      hasWarning: true,
    };
  }
  return base;
}

/**
 * Inspects an EPANET .rpt report body for genuine engine warnings/errors.
 * Never hardcodes "정상 수렴" (normal convergence) - the verdict always derives
 * from the actual report text produced by the engine for the current analysis run.
 */
export function inspectConvergence(reportText?: string | null): ConvergenceInspection {
  if (!reportText || reportText.trim().length === 0) {
    return {
      status: '해석 미실행 (확인 불가)',
      color: '#64748b',
      note: '엔진 보고서가 생성되지 않았습니다.',
      hasWarning: false,
    };
  }

  const hasWarning =
    reportText.includes('WARNING') ||
    reportText.includes('unbalanced') ||
    reportText.includes('System unbalanced') ||
    reportText.includes('Negative pressures') ||
    reportText.includes('cannot be met') ||
    /Error\s+\d+/.test(reportText);

  if (hasWarning) {
    return {
      status: '경고/불균형 발생 (엔진 로그 확인 필요)',
      color: '#dc2626',
      note: '엔진 보고서에 경고 또는 오류가 포함되어 있습니다.',
      hasWarning: true,
    };
  }

  if (reportText.length > 50 && (reportText.includes('Hydraulic Status') || reportText.includes('Analysis begun'))) {
    return {
      status: '수리방정식 정상 수렴 확인',
      color: '#16a34a',
      note: '엔진 보고서에 경고 없이 해석이 완료되었습니다.',
      hasWarning: false,
    };
  }

  return {
    status: '해석 완료 (상세 로그 참조)',
    color: '#2563eb',
    note: '보고서 내용이 짧아 수렴 여부를 완전히 판별할 수 없습니다. 상세 로그를 확인하세요.',
    hasWarning: false,
  };
}