import type { TaskLogEntry, WorkflowStepResult } from "@fusion/core";

export interface TimingEvent {
  timestamp: string;
  durationMs?: number;
  summary: string;
}

function summarizeTimingLabel(entry: TaskLogEntry): string {
  const timingText = entry.action || entry.outcome || "";
  const stripped = timingText
    .replace(/^\[timing\]\s*/i, "")
    .replace(/^\[[^\]]+\]\s*/i, "")
    .replace(/\s+in\s+\d+(?:\.\d+)?ms\b/i, "")
    .replace(/\s+after\s+\d+(?:\.\d+)?ms\b/i, "")
    .trim();
  return stripped || "Timing event";
}

export function extractTimingEvents(logEntries: TaskLogEntry[]): TimingEvent[] {
  return logEntries
    .filter((entry) => {
      const actionText = typeof entry.action === "string" ? entry.action : "";
      const outcomeText = typeof entry.outcome === "string" ? entry.outcome : "";
      return actionText.includes("[timing]") || outcomeText.includes("[timing]");
    })
    .map((entry) => {
      const haystack = `${entry.action ?? ""}\n${entry.outcome ?? ""}`;
      const durationMatch = haystack.match(/(\d+(?:\.\d+)?)ms\b/i);
      const durationMs = durationMatch ? Number(durationMatch[1]) : undefined;
      return {
        timestamp: entry.timestamp,
        durationMs: Number.isFinite(durationMs) ? durationMs : undefined,
        summary: summarizeTimingLabel(entry),
      };
    });
}

export function getTimedDurationMs(logEntries: TaskLogEntry[] | undefined): number | null {
  if (!logEntries || logEntries.length === 0) return null;
  let total = 0;
  let counted = 0;
  for (const event of extractTimingEvents(logEntries)) {
    if (typeof event.durationMs !== "number") continue;
    total += event.durationMs;
    counted += 1;
  }
  return counted > 0 ? total : null;
}

export function parseTimestampToMs(value?: string): number | null {
  if (!value) return null;
  const parsed = Date.parse(value);
  return Number.isFinite(parsed) ? parsed : null;
}

export function getWorkflowRuntimeMs(results: WorkflowStepResult[] | undefined, nowMs: number): number | null {
  if (!results || results.length === 0) return null;

  let total = 0;
  let counted = 0;
  for (const step of results) {
    if (!step.startedAt) continue;
    const startedMs = parseTimestampToMs(step.startedAt);
    if (startedMs == null) continue;

    let endMs: number;
    if (step.completedAt) {
      const completedMs = parseTimestampToMs(step.completedAt);
      if (completedMs == null || completedMs < startedMs) continue;
      endMs = completedMs;
    } else {
      endMs = Math.max(startedMs, nowMs);
    }

    total += endMs - startedMs;
    counted += 1;
  }

  return counted > 0 ? total : null;
}

export function getEndToEndDurationMs(
  executionStartedAt: string | undefined,
  executionCompletedAt: string | undefined,
  nowMs: number,
): number | null {
  const startedMs = parseTimestampToMs(executionStartedAt);
  if (startedMs == null) return null;

  const completedMs = parseTimestampToMs(executionCompletedAt);
  const endMs = completedMs != null && completedMs >= startedMs ? completedMs : nowMs;
  return Math.max(0, endMs - startedMs);
}