// Architecture decisions of a model: one *.archify-decision file each, anywhere
// under the model root. Mirrors the extension's src/model/decisions.ts.
import fs from 'node:fs';
import { isMap, isScalar, isSeq, parseDocument } from '../../vendor/yaml/index.js';

export const DECISION_EXT = '.archify-decision';
export const DECISION_STATUSES = ['proposed', 'accepted', 'superseded', 'rejected'];

const str = (v) => (typeof v === 'string' && v.trim() ? v : undefined);

export function parseDecision(text, file) {
  const problems = [];
  const doc = parseDocument(text, { prettyErrors: false, uniqueKeys: false });
  for (const error of doc.errors) problems.push({ severity: 'error', file, message: `Decision is not valid YAML: ${error.message.split('\n')[0]}`, line: error.linePos?.[0].line ?? 1 });
  if (doc.errors.length) return { problems };
  const lineOf = (offset) => (offset === undefined ? 1 : text.slice(0, offset).split('\n').length);
  const root = doc.contents;
  if (!isMap(root)) return { problems: [{ severity: 'error', file, message: 'A decision file is a mapping with a "decision" block and context, decision and consequences.', line: 1 }] };
  const headNode = root.get('decision', true);
  if (!isMap(headNode)) return { problems: [{ severity: 'error', file, message: 'A decision needs a "decision" block with id, title and status.', line: 1, pointer: '/decision' }] };
  const headPair = root.items.find((p) => isScalar(p.key) && p.key.value === 'decision');
  const headLine = headPair ? lineOf(headPair.key.range?.[0]) : 1;
  const keyLine = (key) => { const pair = headNode.items.find((p) => isScalar(p.key) && p.key.value === key); return pair ? lineOf(pair.key.range?.[0]) : headLine; };
  const list = (key) => {
    const node = headNode.get(key, true);
    const values = []; const lines = [];
    if (isSeq(node)) {
      for (const item of node.items) {
        if (!isScalar(item)) continue;
        if (typeof item.value === 'number') { problems.push({ severity: 'error', file, message: `"${item.value}" in ${key} is a number to YAML. Quote it or use words.`, line: lineOf(item.range?.[0]), pointer: `/decision/${key}` }); continue; }
        if (str(item.value)) { values.push(item.value); lines.push(lineOf(item.range?.[0])); }
      }
    } else if (node !== undefined) problems.push({ severity: 'error', file, message: `"${key}" must be a list.`, line: keyLine(key), pointer: `/decision/${key}` });
    return { values, lines };
  };
  const head = headNode.toJSON();
  if (typeof head.id === 'number') { problems.push({ severity: 'error', file, message: `decision.id ${head.id} is a number to YAML (0001 becomes 1). Quote it ("${head.id}") or use words.`, line: keyLine('id'), pointer: '/decision/id' }); return { problems }; }
  const id = str(head.id);
  if (!id) { problems.push({ severity: 'error', file, message: 'decision.id is missing.', line: headLine, pointer: '/decision/id' }); return { problems }; }
  const status = str(head.status);
  if (status && !DECISION_STATUSES.includes(status)) problems.push({ severity: 'error', file, message: `Unknown status "${status}"; one of ${DECISION_STATUSES.join(', ')}.`, line: keyLine('status'), pointer: '/decision/status' });
  const elements = list('elements'); const diagrams = list('diagrams'); const supersedes = list('supersedes');
  const body = root.toJSON();
  return { problems, decision: { id, title: str(head.title), status, date: head.date === undefined ? undefined : String(head.date), elements: elements.values, diagrams: diagrams.values, supersedes: supersedes.values, context: str(body.context), decision: str(body.decision), consequences: str(body.consequences), file, line: headLine, lines: { id: keyLine('id'), elements: elements.lines, diagrams: diagrams.lines, supersedes: supersedes.lines } } };
}

export function loadDecisions(files, relative) {
  const decisions = {}; const problems = [];
  for (const full of files) {
    const file = relative(full);
    const parsed = parseDecision(fs.readFileSync(full, 'utf8'), file);
    problems.push(...parsed.problems);
    if (!parsed.decision) continue;
    const existing = decisions[parsed.decision.id];
    if (existing) { problems.push({ severity: 'error', file, message: `Decision "${parsed.decision.id}" is defined twice (also in ${existing.file}).`, line: parsed.decision.lines.id }); continue; }
    decisions[parsed.decision.id] = parsed.decision;
  }
  return { decisions, files: files.map(relative), problems };
}

export function effectiveStatus(decision, all) {
  for (const other of Object.values(all)) if (other !== decision && other.supersedes.includes(decision.id) && other.status !== 'rejected') return { status: 'superseded', supersededBy: other.id };
  return { status: decision.status ?? 'proposed' };
}

export function validateDecisions(set, elements, diagramPaths) {
  const problems = [];
  for (const d of Object.values(set.decisions)) {
    d.elements.forEach((id, i) => { if (!elements?.[id]) problems.push({ severity: 'error', file: d.file, message: `Unknown element "${id}": no registry of this model defines it.`, line: d.lines.elements[i], pointer: `/decision/elements/${i}` }); });
    d.diagrams.forEach((p, i) => { if (!diagramPaths.has(p)) problems.push({ severity: 'error', file: d.file, message: `Diagram "${p}" does not exist in this model.`, line: d.lines.diagrams[i], pointer: `/decision/diagrams/${i}` }); });
    d.supersedes.forEach((id, i) => {
      if (!set.decisions[id]) problems.push({ severity: 'error', file: d.file, message: `Decision "${id}" (in supersedes) does not exist in this model.`, line: d.lines.supersedes[i], pointer: `/decision/supersedes/${i}` });
      else if (id === d.id) problems.push({ severity: 'error', file: d.file, message: 'A decision cannot supersede itself.', line: d.lines.supersedes[i], pointer: `/decision/supersedes/${i}` });
    });
  }
  return problems;
}

const NODE_COLLECTIONS = ['components', 'nodes', 'participants', 'states'];
const EDGE_COLLECTIONS = ['connections', 'edges', 'flows', 'transitions', 'messages'];

/** Strips `decisions` keys from a diagram (mutating it) and returns what they pointed at, with problems. */
export function takeDecisionRefs(diagram, { known, inModel, problem }) {
  const refs = [];
  const take = (owner, pointer, attachedTo) => {
    if (!('decisions' in owner)) return;
    const raw = owner.decisions; delete owner.decisions;
    (Array.isArray(raw) ? raw : [raw]).forEach((value, i) => {
      if (value === undefined || value === null) return;
      const at = `${pointer}/decisions/${i}`;
      if (typeof value === 'number') return problem('error', `Decision id ${value} is a number to YAML (0001 becomes 1). Quote it ("${value}") or use words.`, at);
      const id = String(value);
      if (!inModel) problem('error', `Decision "${id}" cannot be resolved: no main.archify above this file.`, at);
      else if (known && !known.has(id)) problem('error', `Unknown decision "${id}": no .archify-decision file of this model defines it.`, at);
      refs.push({ id, pointer: at, attachedTo });
    });
  };
  take(diagram, '', { kind: 'diagram' });
  for (const key of NODE_COLLECTIONS) if (Array.isArray(diagram[key])) diagram[key] = diagram[key].map((item, index) => { if (!item || typeof item !== 'object') return item; const copy = { ...item }; take(copy, `/${key}/${index}`, { kind: 'node', id: copy.id ?? copy.ref ?? String(index) }); return copy; });
  for (const key of EDGE_COLLECTIONS) if (Array.isArray(diagram[key])) diagram[key] = diagram[key].map((item, index) => { if (!item || typeof item !== 'object') return item; const copy = { ...item }; take(copy, `/${key}/${index}`, { kind: 'edge', from: copy.from ?? '', to: copy.to ?? '', label: copy.label }); return copy; });
  return refs;
}