/**
 * Situation Graph schema — v0.4 experiment.
 * Defines types for an evolving multi-turn situation reconstruction graph.
 * Plain TypeScript interfaces implemented as Zod schemas for runtime validation.
 */

import { z } from "zod";

// ── Enums ────────────────────────────────────────────

export const SituationKind = /** @type {const} */ ({
  observation: "observation",
  reported_claim: "reported_claim",
  metric: "metric",
  state: "state",
  transition: "transition",
  relationship: "relationship",
  assumption: "assumption",
  unknown: "unknown",
  conclusion: "conclusion",
});

export const SituationStatus = /** @type {const} */ ({
  known: "known",
  unknown: "unknown",
  provisional: "provisional",
  supported: "supported",
  weakened: "weakened",
  contradicted: "contradicted",
  resolved: "resolved",
});

export const ConfidenceLevel = /** @type {const} */ ({
  low: "low",
  medium: "medium",
  high: "high",
});

// ── SituationNode ────────────────────────────────────

export const situationNodeSchema = z.object({
  id: z.string().min(1),
  label: z.string().min(1),
  description: z.string().min(1),
  kind: z.enum(Object.values(SituationKind)),
  status: z.enum(Object.values(SituationStatus)),
  confidence: z.enum(Object.values(ConfidenceLevel)),
  value: z.union([z.string(), z.number(), z.null()]).nullable().optional(),
  unit: z.string().nullable().optional(),
  evidenceIds: z.array(z.string()).default([]),
  dependsOn: z.array(z.string()).default([]),
  affects: z.array(z.string()).default([]),
  parentId: z.string().nullable().optional(),
  childIds: z.array(z.string()).default([]),
});

/** @typedef {z.infer<typeof situationNodeSchema>} SituationNode */

// ── SituationEdge ────────────────────────────────────

export const SituationRelationship = /** @type {const} */ ({
  supports: "supports",
  weakens: "weakens",
  contradicts: "contradicts",
  depends_on: "depends_on",
  causes: "causes",
  may_cause: "may_cause",
  measures: "measures",
  compares_with: "compares_with",
  updates: "updates",
  other: "other",
});

export const situationEdgeSchema = z.object({
  id: z.string().min(1),
  fromNodeId: z.string().min(1),
  toNodeId: z.string().min(1),
  relationship: z.enum(Object.values(SituationRelationship)),
  confidence: z.enum(Object.values(ConfidenceLevel)),
  description: z.string().min(1),
});

/** @typedef {z.infer<typeof situationEdgeSchema>} SituationEdge */

// ── SituationGraph ───────────────────────────────────

export const situationGraphSchema = z.object({
  centralStatement: z.string().min(1),
  nodes: z.array(situationNodeSchema).min(1),
  edges: z.array(situationEdgeSchema).default([]),
  activeUnknownNodeId: z.string().nullable(),
  resolvedNodeIds: z.array(z.string()).default([]),
  currentSummary: z.string().min(1),
});

/** @typedef {z.infer<typeof situationGraphSchema>} SituationGraph */

// ── GraphUpdate (change set) ────────────────────────

const graphUpdateNodeChangeSchema = z.object({
  nodeId: z.string().min(1),
  previousStatus: z.enum(Object.values(SituationStatus)).nullable().optional(),
  newStatus: z.enum(Object.values(SituationStatus)).nullable().optional(),
  previousValue: z.union([z.string(), z.number(), z.null()]).nullable().optional(),
  newValue: z.union([z.string(), z.number(), z.null()]).nullable().optional(),
  reason: z.string().min(1),
});

export const graphUpdateSchema = z.object({
  addedNodes: z.array(situationNodeSchema).default([]),
  updatedNodes: z.array(graphUpdateNodeChangeSchema).default([]),
  addedEdges: z.array(situationEdgeSchema).default([]),
  removedEdgeIds: z.array(z.string()).default([]),
  resolvedUnknownNodeIds: z.array(z.string()).default([]),
  affectedNodeIds: z.array(z.string()).default([]),
});

/** @typedef {z.infer<typeof graphUpdateSchema>} GraphUpdate */

// ── API request / response schemas ───────────────────

export const startCaseRequestSchema = z.object({
  scenario: z.string().min(1).max(10000),
  promptVersion: z.string().optional(),
});

export const updateCaseRequestSchema = z.object({
  situationGraph: situationGraphSchema,
  previousQuestion: z.string().min(1),
  answer: z.string().min(1).max(5000),
  promptVersion: z.string().optional(),
});

// ── Helpers ──────────────────────────────────────────

/** Generate a short deterministic ID from a label */
export function makeNodeId(label) {
  return "n" + Math.abs(hashString(label)).toString(36).slice(0, 7);
}

function hashString(str) {
  let h = 0;
  for (let i = 0; i < str.length; i++) {
    h = (Math.imul(31, h) + str.charCodeAt(i)) | 0;
  }
  return h;
}

/** Create a minimal valid node — used in tests and fixtures */
export function makeNode(opts) {
  const id = opts.id || makeNodeId(opts.label);
  return situationNodeSchema.parse({
    id,
    label: opts.label,
    description: opts.description ?? opts.label,
    kind: opts.kind ?? "observation",
    status: opts.status ?? "unknown",
    confidence: opts.confidence ?? "medium",
    value: opts.value ?? null,
    unit: opts.unit ?? null,
    evidenceIds: opts.evidenceIds ?? [],
    dependsOn: opts.dependsOn ?? [],
    affects: opts.affects ?? [],
    parentId: opts.parentId ?? null,
    childIds: opts.childIds ?? [],
  });
}

/** Create a minimal valid edge — used in tests and fixtures */
export function makeEdge(opts) {
  return situationEdgeSchema.parse({
    id: opts.id || "e" + opts.fromNodeId.slice(0,3) + "-" + opts.toNodeId.slice(0,3),
    fromNodeId: opts.fromNodeId,
    toNodeId: opts.toNodeId,
    relationship: opts.relationship ?? "supports",
    confidence: opts.confidence ?? "medium",
    description: opts.description ?? opts.fromNodeId + " -> " + opts.toNodeId,
  });
}

/** Build a minimal valid graph structure */
export function makeGraph(opts) {
  return situationGraphSchema.parse({
    centralStatement: opts.centralStatement || "",
    nodes: opts.nodes ?? [],
    edges: opts.edges ?? [],
    activeUnknownNodeId: opts.activeUnknownNodeId ?? null,
    resolvedNodeIds: opts.resolvedNodeIds ?? [],
    currentSummary: opts.currentSummary || "",
  });
}