/**
 * Pipeline Checkpoint System — Crash Recovery
 * 
 * Problem: Pipeline crashes at company #15 → restarts → 
 *          processes company #1-14 again = wasted API calls + duplicates
 * 
 * Solution: Save checkpoint after each major stage.
 *           On restart, resume from last checkpoint.
 * 
 * Stages (in order):
 *   scraped → filtered → contacts_found → profiled → scored → completed
 */

import { getSupabaseClient } from "../supabase/client";
import { logger } from "../utils/logger";

export type PipelineStage =
  | "discovered"       // found in search results
  | "scraped"          // website scraped
  | "filtered"         // passed Gate 1 + 2
  | "contacts_found"   // decision makers identified
  | "emails_verified"  // emails found and verified
  | "profiled"         // LLM profile generated
  | "scored"           // score computed
  | "completed";       // fully processed

/**
 * Save checkpoint for a company in a specific run.
 * Stores intermediate data so pipeline can resume from this point.
 */
export async function saveCheckpoint(
  runId: string,
  domain: string,
  stage: PipelineStage,
  stageData: Record<string, unknown> = {}
): Promise<void> {
  const db = getSupabaseClient();
  
  const { error } = await db.from("pipeline_checkpoints").upsert(
    {
      run_id: runId,
      company_domain: domain,
      stage,
      stage_data: stageData,
      completed: stage === "completed",
      updated_at: new Date().toISOString(),
    },
    { onConflict: "run_id,company_domain" }
  );

  if (error) {
    logger.warn({ domain, stage, error: error.message }, "Checkpoint save failed — non-critical");
  }
}

/**
 * Get the last checkpoint for a domain in a run.
 * Returns null if no checkpoint exists (fresh start).
 */
export async function getCheckpoint(
  runId: string,
  domain: string
): Promise<{ stage: PipelineStage; stageData: Record<string, unknown> } | null> {
  const db = getSupabaseClient();
  
  const { data } = await db
    .from("pipeline_checkpoints")
    .select("stage, stage_data")
    .eq("run_id", runId)
    .eq("company_domain", domain)
    .maybeSingle();

  if (!data) return null;
  return { stage: data.stage as PipelineStage, stageData: data.stage_data ?? {} };
}

/**
 * Check if a domain was already fully processed in ANY recent run.
 * Prevents re-processing across separate runs (not just within one run).
 */
export async function isAlreadyProcessed(domain: string, withinDays = 30): Promise<boolean> {
  const db = getSupabaseClient();
  
  const cutoff = new Date();
  cutoff.setDate(cutoff.getDate() - withinDays);

  const { data } = await db
    .from("pipeline_checkpoints")
    .select("id")
    .eq("company_domain", domain)
    .eq("completed", true)
    .gte("updated_at", cutoff.toISOString())
    .limit(1)
    .maybeSingle();

  return !!data;
}

/**
 * Get all incomplete companies in a run (for resume).
 * Returns list of domains and their last stage.
 */
export async function getIncompleteCompanies(
  runId: string
): Promise<{ domain: string; stage: PipelineStage; stageData: Record<string, unknown> }[]> {
  const db = getSupabaseClient();
  
  const { data } = await db
    .from("pipeline_checkpoints")
    .select("company_domain, stage, stage_data")
    .eq("run_id", runId)
    .eq("completed", false);

  return (data ?? []).map((d) => ({
    domain: d.company_domain,
    stage: d.stage as PipelineStage,
    stageData: d.stage_data ?? {},
  }));
}

/**
 * Stage ordering — used to determine if we can skip ahead.
 */
const STAGE_ORDER: PipelineStage[] = [
  "discovered", "scraped", "filtered", "contacts_found",
  "emails_verified", "profiled", "scored", "completed",
];

export function isStageComplete(currentStage: PipelineStage, requiredStage: PipelineStage): boolean {
  return STAGE_ORDER.indexOf(currentStage) >= STAGE_ORDER.indexOf(requiredStage);
}

/**
 * Helper to determine where to resume processing for a company.
 */
export function getResumePoint(checkpoint: { stage: PipelineStage } | null): PipelineStage {
  if (!checkpoint) return "discovered";
  
  // Resume from the NEXT stage after the last completed one
  const idx = STAGE_ORDER.indexOf(checkpoint.stage);
  if (idx < 0 || idx >= STAGE_ORDER.length - 1) return "discovered";
  return STAGE_ORDER[idx + 1];
}