import { useEffect, useState } from 'react'
import { useZino } from '../api/provider.jsx'
import ClampText from './ClampText.jsx'
import { APP_ID, STAGES, baseFieldId } from '../api/config.js'
import './Timeline.css'

/** Which employee holds which role — used to badge an entry as machine work. */
const AI_ROLES = {
  ai_intake: 'Intake & Attribution',
  ai_engage: 'Engage',
  ai_kyc: 'KYC & Evidence',
  ai_advisor: 'Advisor',
  ai_uw_referral: 'Underwriting Referral',
}

/**
 * The fields worth surfacing per activity — an agent's reasoning, a rule's
 * output, a call's notes. Everything else stays in the file below; a timeline
 * that shows every field is a table, not a story.
 *
 * Keyed on the BASE field id. An audit row's data is keyed by the ACTIVITY's
 * field ids, which carry a per-form suffix — the call notes arrive as
 * `contact_notes_2`, the document request as `documents_notes_3`. Matching the
 * global ids directly, as this did, meant almost nothing ever matched: the
 * timeline showed a bare list of activity names, and the one narrative line
 * that did appear was an accident (a DATA_UPDATE row happens to write the
 * unsuffixed key).
 */
const NARRATIVE = [
  ['attribution_reason', 'Attribution'],
  ['eligibility_reason', 'Eligibility'],
  ['dedupe_match_ref', 'Duplicate of'],
  ['contact_notes', 'Call'],
  ['ai_recommendation_rationale', 'Recommendation'],
  ['quoted_breakup', 'How the premium was reached'],
  ['kyc_mismatch_notes', 'KYC'],
  ['referral_analysis', 'Referral analysis'],
  ['uw_decision_notes', 'Underwriting decision'],
  ['documents_notes', 'Documents'],
  ['lost_reason', 'Why it was dropped'],
  ['resume_note', 'Why now'],
]

const MONEY = new Set(['quoted_premium', 'commission_amount', 'sme_value_at_risk', 'motor_idv'])

/** Document slots, in the order they are worth reading. Labels are shorter than
 *  the workflow's own — "Registration Certificate (RC)" is a chip, not a form
 *  label — and a slot missing from here still renders under its server label. */
const DOC_LABELS = {
  doc_rc: 'RC',
  doc_prev_policy: 'Expiring policy',
  doc_pan: 'PAN',
  doc_gst_cert: 'GST certificate',
  doc_udyam_cert: 'Udyam certificate',
  doc_address_proof: 'Address proof',
  doc_premises_proof: 'Premises proof',
  doc_stock_statement: 'Stock statement',
  doc_premises_photos: 'Premises photos',
  doc_vehicle_photos: 'Vehicle photos',
  doc_financials: 'Financials',
}

const FILE_TYPES = new Set(['file', 'ocr'])

function when(ts) {
  if (!ts) return ''
  const d = new Date(ts)
  const mins = Math.round((Date.now() - d.getTime()) / 60000)
  const rel = mins < 1 ? 'just now'
    : mins < 60 ? `${mins}m ago`
    : mins < 1440 ? `${Math.round(mins / 60)}h ago`
    : `${Math.round(mins / 1440)}d ago`
  return `${d.toLocaleString('en-IN', { day: 'numeric', month: 'short', hour: '2-digit', minute: '2-digit' })} · ${rel}`
}

/**
 * Last resort for a step whose activity_name did not come back. Without this
 * the timeline — the screen the whole product is demonstrated on — prints a
 * raw slug like "zk-act-doc-reminder" in the middle of an otherwise readable
 * story. Turning it into "Doc Reminder" is a guess, but it is a guess that
 * reads as English.
 */
function prettyUid(uid) {
  if (!uid) return 'Step'
  return String(uid)
    .replace(/^zk-act-/, '')
    .split('-')
    .filter(Boolean)
    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
    .join(' ')
}

/** An uploaded file, as the platform stores it. */
function filesIn(value) {
  if (!Array.isArray(value)) return []
  return value.filter((f) => f && typeof f === 'object' && f.uuid)
}

export default function Timeline({ instanceId }) {
  const { client } = useZino()
  const [rows, setRows] = useState(null)
  const [err, setErr] = useState(null)
  // DATA_UPDATE entries are the platform writing fields, not anyone deciding
  // anything. They are the bulk of a busy trail and they are hidden until asked
  // for — the story is what people and agents did.
  const [showSys, setShowSys] = useState(false)

  useEffect(() => {
    let dead = false
    client.audit(instanceId)
      .then((r) => { if (!dead) setRows(Array.isArray(r) ? r : (r?.data ?? [])) })
      .catch((e) => { if (!dead) setErr(e) })
    return () => { dead = true }
  }, [client, instanceId])

  if (err) return <div className="tl__err">Could not load the timeline — {err.status} {err.message}</div>
  if (!rows) return <p className="tl__loading">Loading the timeline…</p>
  if (!rows.length) return <p className="tl__loading">Nothing has happened yet.</p>

  // Oldest first: a timeline reads forwards.
  const ordered = [...rows].sort((a, b) => String(a.created_at).localeCompare(String(b.created_at)))

  // ONE SUBMISSION WRITES SEVERAL ROWS. The platform records each stage of a
  // submission separately, told apart by execution_state:
  //
  //   zk-act-qualify   TRIGGER_PERFORMED     the trigger's commit
  //   zk-act-qualify   TRIGGER_PERFORMED     ...again, on the settle path
  //   zk-act-qualify   zk-state-qualified    the one that moved the lead
  //
  // Rendered literally that is "Qualify Lead" three times in a row, which
  // reads as the AI having done the same thing three times. Only the row
  // carrying a real state means anything to somebody reading the file.
  //
  // Collapsed on (same activity, within fifteen seconds) rather than on the
  // execution_state alone, because a genuine repeat has to survive: Collect
  // Documents really is performed twice on a lead whose first upload was
  // incomplete, and those are minutes apart, not milliseconds.
  //
  // The kept row takes the EARLIEST timestamp — when the operator acted — and
  // whichever state and payload is actually populated.
  const isStage = (v) => STAGES.some((s) => s.uid === v)
  const SAME_SUBMISSION_MS = 15000

  const merged = []
  for (const r of ordered) {
    // Look BACK for a match rather than only at the previous entry: the
    // platform interleaves a DATA_UPDATE row between the two halves of one
    // submission, so the rows to merge are near each other in time but not
    // adjacent in the list.
    let at = -1
    for (let i = merged.length - 1; i >= 0; i--) {
      if (Date.parse(r.created_at) - Date.parse(merged[i].created_at) >= SAME_SUBMISSION_MS) break
      if (merged[i].activity_id === r.activity_id) { at = i; break }
    }

    if (at >= 0) {
      const prev = merged[at]
      merged[at] = {
        ...prev,
        // The settle row is the one that names the resulting stage.
        execution_state: isStage(r.execution_state) ? r.execution_state : prev.execution_state,
        // Whichever row actually carries the submission and the AI's working.
        data: (r.data && Object.keys(r.data).length) ? r.data : prev.data,
        fields: (r.fields && r.fields.length) ? r.fields : prev.fields,
        user_name: prev.user_name || r.user_name,
        user_roles: (prev.user_roles && prev.user_roles.length) ? prev.user_roles : r.user_roles,
        created_at: prev.created_at,
      }
      continue
    }
    merged.push(r)
  }

  let lastStage = null
  const items = merged.map((r, i) => {
    const roles = r.user_roles || []
    // SYSTEM FIRST. A DATA_UPDATE row inherits the roles of whoever caused it,
    // so an AI's own field write matched AI_ROLES, was classed as agent work,
    // and appeared in the trail as an entry titled "Data updated" — twice,
    // while the toggle below still offered to reveal two others. The row's
    // activity id is what says it is bookkeeping; the roles say who triggered
    // the bookkeeping, which is a different question.
    const isSystem = r.activity_id === 'DATA_UPDATE'
    const aiRole = roles.find((x) => AI_ROLES[x])
    const kind = isSystem ? 'sys' : aiRole ? 'ai' : 'human'

    /**
     * The value view. `fields[]` is the platform's own typed rendering of the
     * submission — one entry per configured field with its label, data type and
     * value — and it is what makes a file field knowable as a file. `data` is
     * the raw untyped fallback for a row the workflow could not resolve.
     */
    const fields = Array.isArray(r.fields) && r.fields.length
      ? r.fields
      : Object.entries(r.data || {}).map(([k, v]) => ({ field_id: k, label: '', data_type: '', value: v }))

    const byBase = new Map()
    for (const f of fields) {
      const base = baseFieldId(f.field_id)
      // `_system` is the platform's own marker on every submission.
      if (base === '_system') continue
      if (!byBase.has(base)) byBase.set(base, f)
    }

    // What was attached. This is the answer to "show me that the documents
    // were captured": the names, from the submission that carried them, each
    // one openable.
    const docs = []
    for (const [base, f] of byBase) {
      if (!FILE_TYPES.has(f.data_type) && !base.startsWith('doc_')) continue
      for (const file of filesIn(f.value)) {
        docs.push({ slot: DOC_LABELS[base] || f.label || base, ...file })
      }
    }

    const stage = STAGES.find((s) => s.uid === r.execution_state)
    // A self-loop — Capture Motor Risk runs inside Document Pending and settles
    // back into it — is not a move, and printing "→ Document Pending" against
    // four consecutive entries reads as the lead bouncing.
    const moved = stage && stage.uid !== lastStage
    if (stage) lastStage = stage.uid

    return {
      key: r.id ?? i,
      kind,
      actor: aiRole ? AI_ROLES[aiRole] : (r.user_name || 'System'),
      what: isSystem ? 'Data updated' : (r.activity_name || prettyUid(r.activity_id)),
      stage: moved ? stage : null,
      when: when(r.created_at),
      docs,
      narrative: NARRATIVE
        .map(([k, label]) => [label, byBase.get(k)?.value])
        .filter(([, v]) => v !== undefined && v !== null && typeof v !== 'object' && String(v).trim() !== ''),
      figures: [...byBase]
        .filter(([base, f]) => MONEY.has(base) && f.value)
        .map(([base, f]) => [base.replace(/_/g, ' '), '₹' + Number(f.value).toLocaleString('en-IN')]),
    }
  })

  const sysCount = items.filter((it) => it.kind === 'sys').length
  const visible = showSys ? items : items.filter((it) => it.kind !== 'sys')

  return (
    <>
      {sysCount ? (
        <button type="button" className="tl__toggle" onClick={() => setShowSys((v) => !v)}>
          {showSys ? 'Hide' : 'Show'} {sysCount} system update{sysCount === 1 ? '' : 's'}
        </button>
      ) : null}

      <ol className="tl">
        {visible.map((it) => (
          <li key={it.key} className={'tl__item tl__item--' + it.kind}>
            <span className="tl__dot" aria-hidden="true" />
            <div className="tl__body">
              <div className="tl__head">
                <strong className="tl__what">{it.what}</strong>
                {it.stage ? <span className="tl__stage">→ {it.stage.name}</span> : null}
              </div>
              <div className="tl__meta">
                <span className={'tl__who tl__who--' + it.kind}>
                  {it.kind === 'ai' ? 'AI' : it.kind === 'sys' ? 'system' : 'person'} · {it.actor}
                </span>
                <span className="tl__when">{it.when}</span>
              </div>

              {/* What was received, named and openable. The count is stated
                  rather than left to be inferred from a list — "3 documents
                  received" is the sentence the operator is looking for. */}
              {it.docs.length ? (
                <div className="tl__docs">
                  <span className="tl__docshead">
                    {it.docs.length} document{it.docs.length === 1 ? '' : 's'} received
                  </span>
                  <div className="tl__doclist">
                    {it.docs.map((d) => (
                      <a
                        key={d.uuid}
                        className="tl__doc"
                        href={`${client.baseUrl}/app/${APP_ID}/view/files/${d.uuid}/preview`}
                        target="_blank"
                        rel="noreferrer"
                        title={d.original_name}
                      >
                        <svg viewBox="0 0 14 14" aria-hidden="true">
                          <path d="M3.5 1.5h4.2L11 4.8v7.7H3.5z" fill="none" stroke="currentColor" strokeWidth="1.2"
                                strokeLinejoin="round" />
                          <path d="M7.6 1.6v3.3H11" fill="none" stroke="currentColor" strokeWidth="1.2"
                                strokeLinejoin="round" />
                        </svg>
                        {d.slot}
                      </a>
                    ))}
                  </div>
                </div>
              ) : null}

              {it.narrative.map(([label, v]) => (
                <div className="tl__say" key={label}>
                  <span className="tl__saylabel">{label}</span>
                  <ClampText text={String(v)} title={`${label} — ${it.what}`} lines={2} threshold={120} />
                </div>
              ))}

              {it.figures.length ? (
                <div className="tl__figs">
                  {it.figures.map(([k, v]) => (
                    <span key={k}><em>{k}</em> {v}</span>
                  ))}
                </div>
              ) : null}
            </div>
          </li>
        ))}
      </ol>
    </>
  )
}