import { Scale } from "lucide-react";
import { useEffect, useMemo, useRef, useState } from "react";
import { FormGrid,
  Button,
  ConfirmDialog,
  Dialog,
  DismissibleAlert,
  DocumentationHelpLink,
  FormField,
  i18nMessage,
  type ApiSettings
} from "@govoplan/core-webui";
import {
  recordCaseDecision,
  type CaseDecisionResult,
  type CaseRecord
} from "../../api/cases";
import { CASES_FIELDS_DOCUMENTATION } from "./interfacePatterns";


export default function CaseDecisionDialog({
  settings,
  record,
  purpose,
  open,
  onClose,
  onSaved
}: {
  settings: ApiSettings;
  record: CaseRecord;
  purpose: string;
  open: boolean;
  onClose: () => void;
  onSaved: (result: CaseDecisionResult) => void;
}) {
  const [decisionType, setDecisionType] = useState("");
  const [effectiveAt, setEffectiveAt] = useState("");
  const [operativeResult, setOperativeResult] = useState("");
  const [reasoning, setReasoning] = useState("");
  const [conditions, setConditions] = useState("");
  const [changeReason, setChangeReason] = useState("");
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState("");
  const [confirmOpen, setConfirmOpen] = useState(false);
  const idempotencyKey = useRef(crypto.randomUUID());

  useEffect(() => {
    if (!open) return;
    setDecisionType(defaultDecisionType(record));
    setEffectiveAt(dateTimeLocalValue(new Date()));
    setOperativeResult("");
    setReasoning("");
    setConditions("");
    setChangeReason("");
    setError("");
    setConfirmOpen(false);
    idempotencyKey.current = crypto.randomUUID();
  }, [open, record]);

  const disabledReason = useMemo(() => {
    if (busy) return "The formal Decision is being recorded.";
    if (
      !decisionType.trim()
      || !effectiveAt
      || !operativeResult.trim()
      || !reasoning.trim()
      || !changeReason.trim()
    ) {
      return "Complete the Decision type, effective time, result, reasoning, and change reason.";
    }
    return undefined;
  }, [busy, changeReason, decisionType, effectiveAt, operativeResult, reasoning]);

  async function save() {
    if (disabledReason) return;
    setBusy(true);
    setError("");
    try {
      const result = await recordCaseDecision(settings, record.reference.object_id, {
        expected_case_revision: record.revision,
        effective_at: new Date(effectiveAt).toISOString(),
        decision_type: decisionType.trim(),
        operative_result: operativeResult.trim(),
        reasoning: reasoning.trim(),
        conditions: conditions.split("\n").map((item) => item.trim()).filter(Boolean),
        change_reason: changeReason.trim(),
        idempotency_key: idempotencyKey.current,
        purpose
      });
      setConfirmOpen(false);
      onSaved(result);
      onClose();
    } catch (reason) {
      setConfirmOpen(false);
      setError(reason instanceof Error ? reason.message : "The formal Decision could not be recorded.");
    } finally {
      setBusy(false);
    }
  }

  return (
    <>
      <Dialog
        open={open}
        title={i18nMessage("i18n:govoplan-cases.decision_title", { value0: record.case_number })}
        titleHelp={<DocumentationHelpLink reference={CASES_FIELDS_DOCUMENTATION} />}
        onClose={onClose}
        closeDisabled={busy}
        portal
        className="case-decision-dialog"
        footer={
          <>
            <Button disabled={busy} onClick={onClose}>Cancel</Button>
            <Button
              variant="primary"
              disabledReason={disabledReason}
              onClick={() => setConfirmOpen(true)}
              helpContextId="cases.action.decide"
            >
              <Scale size={16} aria-hidden="true" />
              Record decision
            </Button>
          </>
        }
      >
        <div className="case-decision-content" data-help-context-id="cases.decision.editor">
          {error ? <DismissibleAlert tone="danger" resetKey={error}>{error}</DismissibleAlert> : null}
          <p className="case-decision-explanation">
            The server verifies your current acting assignment, the effective Mandate, the exact Case revision, evidence, and legal basis before recording the outcome.
          </p>
          <FormGrid columns={2} gap="small" collapseAt="workspace" className="case-decision-grid">
            <FormField label="Decision type" documentation={CASES_FIELDS_DOCUMENTATION}>
              <input
                value={decisionType}
                disabled={busy}
                maxLength={120}
                onChange={(event) => setDecisionType(event.target.value)}
              />
            </FormField>
            <FormField label="Effective at" documentation={CASES_FIELDS_DOCUMENTATION}>
              <input
                type="datetime-local"
                value={effectiveAt}
                disabled={busy}
                onChange={(event) => setEffectiveAt(event.target.value)}
              />
            </FormField>
          </FormGrid>
          <FormField label="Operative result" documentation={CASES_FIELDS_DOCUMENTATION}>
            <textarea
              rows={4}
              value={operativeResult}
              disabled={busy}
              maxLength={20_000}
              onChange={(event) => setOperativeResult(event.target.value)}
            />
          </FormField>
          <FormField label="Reasoning" documentation={CASES_FIELDS_DOCUMENTATION}>
            <textarea
              rows={7}
              value={reasoning}
              disabled={busy}
              maxLength={50_000}
              onChange={(event) => setReasoning(event.target.value)}
            />
          </FormField>
          <FormField label="Conditions (one per line)" documentation={CASES_FIELDS_DOCUMENTATION}>
            <textarea
              rows={3}
              value={conditions}
              disabled={busy}
              onChange={(event) => setConditions(event.target.value)}
            />
          </FormField>
          <FormField label="Change reason" documentation={CASES_FIELDS_DOCUMENTATION}>
            <input
              value={changeReason}
              disabled={busy}
              maxLength={1_000}
              onChange={(event) => setChangeReason(event.target.value)}
            />
          </FormField>
        </div>
      </Dialog>
      <ConfirmDialog
        open={confirmOpen}
        title="Record formal Decision"
        message="Record this formal outcome against the exact Case revision? The protected result and reasoning become an immutable Decisions revision."
        confirmLabel="Record decision"
        busy={busy}
        onCancel={() => setConfirmOpen(false)}
        onConfirm={() => void save()}
      />
    </>
  );
}


function defaultDecisionType(record: CaseRecord): string {
  const resultRefs = Array.isArray(record.metadata.result_refs)
    ? record.metadata.result_refs
    : [];
  const result = resultRefs.find((item): item is string => typeof item === "string");
  if (result) return result.replace(/^decision:/, "");
  return record.case_type_key.replace(/-application$/, "");
}


function dateTimeLocalValue(value: Date): string {
  const local = new Date(value.getTime() - value.getTimezoneOffset() * 60_000);
  return local.toISOString().slice(0, 16);
}