import { standardNativeBackends, type NativeExecutionBackend } from "./native-backends.js";
import type {
  WorkspaceRevision,
  ExecutionContract,
  ValueType,
  Binding,
  DependencyBinding,
  EdgeTraversal,
  InterfaceRevisionId,
  AtomId,
  OperationId,
} from "../capability-model/types.js";
import { validateWorkspaceRevision } from "../capability-model/validation.js";
import { canonicalJson, contentDigest } from "../capability-model/evolution.js";
import { resolveForwardedBinding } from "../capability-model/forwarding.js";
import { linkQueries, type LinkedQuery } from "../query/link.js";
import { type BindingSchema } from "../bindings/index.js";
import { unsupportedQueryOperator } from "./query-operators.js";
import { packageBuildContexts } from "./build-contract.js";

export class ExecutionPlanError extends Error {
  constructor(
    readonly code: string,
    readonly path: string,
    message: string,
  ) {
    super(`${code} ${path}: ${message}`);
    this.name = "ExecutionPlanError";
  }
}
export const hexDigest = (value: unknown): string => contentDigest(value).slice("sha256:".length);
const sorted = <T>(values: readonly T[], key: (value: T) => string): T[] =>
  [...values].sort((a, b) => (key(a) < key(b) ? -1 : key(a) > key(b) ? 1 : 0));
export const publicOperationKey = (atom: string, iface: string, operation: string): string =>
  JSON.stringify([atom, iface, operation]);
export type DataDependency =
  | { kind: "state"; slot: string; via?: EdgeTraversal }
  | { kind: "edge"; edge: string; projection: string; via?: EdgeTraversal }
  | { kind: "operation"; operation: string; port: string; via?: EdgeTraversal }
  | { kind: "query"; query: string; port: string };
export interface PlannedOperation {
  key: string;
  atomId: string;
  interfaceRevisionId: string;
  operationId: string;
  scope: "object" | "class";
  execution: ExecutionContract;
  /** Targets available for this complete installed implementation/dependency closure. */
  availableTargets: string[];
  input: ValueType;
  output: ValueType;
  /** Concrete target after public forwarding. Never chosen by a runtime caller. */
  binding: Exclude<Binding, { kind: "interface" }>;
  dependencies: DataDependency[];
}
export interface PlannedQuery {
  id: string;
  query: LinkedQuery;
  /** Query-selected getter entrypoints; dependency traversal supplies canonical inputs. */
  operations: string[];
  /** Local query roots that admission must support, in addition to selected wire outputs. */
  admittedOperations: string[];
}
export interface PlanPackage {
  modules?: (NonNullable<WorkspaceRevision["packageImports"][number]["modules"]>[number] & {
    contract: string;
    subject?: import("../capability-model/types.js").ObjectExpectation;
    typeArguments?: readonly unknown[];
    requiredInterfaces?: readonly string[];
  })[];
  controllers?: NonNullable<WorkspaceRevision["packageImports"][number]["controllers"]>;
  components?: { id: string; displayName: string; subject: InterfaceRevisionId; runtime: "react" }[];
  revision: string;
  source: WorkspaceRevision["packageImports"][number]["source"];
  sourceDigest: string;
  bindingDigest: string;
  exports: { id: string; execution: ExecutionContract }[];
}

export interface ExecutionPlanDefinition {
  presentations?: NonNullable<WorkspaceRevision["presentations"]>;
  codec: "camino-execution-plan-v1";
  workspace: WorkspaceRevision;
  bindingSchema: BindingSchema;
  packages: PlanPackage[];
  owners: { id: string; atom: string; interface: string; initialization: unknown; storage: unknown }[];
  operations: PlannedOperation[];
  queries: PlannedQuery[];
  profiles: { slot: string; profile: string }[];
  versions: {
    value: "camino-value-v1";
    reference: "camino-ref-v1";
    ports: "quixos-transaction-ports-v1";
    crdt: "camino-automerge-3.4.1-structured-v1";
  };
}
export interface ExecutionPlan {
  definition: ExecutionPlanDefinition;
  digest: string;
}
export const executionVersions: ExecutionPlanDefinition["versions"] = {
  value: "camino-value-v1",
  reference: "camino-ref-v1",
  ports: "quixos-transaction-ports-v1",
  crdt: "camino-automerge-3.4.1-structured-v1",
};
/** Selection only: the coordinator separately verifies the caller's grant and receiver witness. */
export function resolvePlannedOperation(
  plan: ExecutionPlan,
  atom: string,
  iface: string,
  operation: string,
): PlannedOperation {
  const key = publicOperationKey(atom, iface, operation);
  const selected = plan.definition.operations.find((entry) => entry.key === key);
  if (!selected) throw new ExecutionPlanError("UNINSTALLED_OPERATION", key, "No installed public operation binding");
  return selected;
}

/** Bound argument/state codec subset. A parsed type alone does not mean a runtime implements it. */
function checkValue(type: ValueType, path: string, allowChange = false): void {
  switch (type.kind) {
    case "variant":
      for (const [label, entry] of Object.entries(type.cases)) checkValue(entry.value, `${path}.${label}`, allowChange);
      return;
    case "scalar":
    case "object-ref":
      return;
    case "builtin":
      if (type.name === "unit") return;
      break;
    case "optional":
    case "list":
      checkValue(type.value, path, allowChange);
      return;
    case "record":
      for (const [name, field] of Object.entries(type.fields)) checkValue(field, `${path}.${name}`, allowChange);
      return;
    case "change":
      if (allowChange) {
        checkValue(type.value, path);
        return;
      }
      break;
  }
  throw new ExecutionPlanError("UNSUPPORTED_PORTABLE_CODEC", path, `Portable execution does not support ${type.kind}`);
}

/** Compile declarations into a closed dispatch/dependency graph before artifact selection. */
export function compileExecutionPlan(
  input: WorkspaceRevision,
  backends: readonly NativeExecutionBackend[] = standardNativeBackends,
): ExecutionPlan {
  const workspace = structuredClone(input);
  const issues = validateWorkspaceRevision(workspace);
  if (issues.length)
    throw new ExecutionPlanError(
      "INVALID_WORKSPACE",
      workspace.id,
      issues.map((i) => `${i.path}: ${i.message}`).join("\n"),
    );
  const interfaces = new Map(workspace.interfaceImports.map((i) => [i.revisionId, i]));
  const packages = new Map(workspace.packageImports.map((p) => [p.revisionId, p]));
  const attachments = [...workspace.sharedAttachments, ...workspace.conformances.flatMap((c) => c.privateAttachments)];
  for (const pkg of workspace.packageImports)
    for (const entry of pkg.exports)
      if (entry.execution && entry.execution.kind !== "remote") {
        checkValue(entry.inputType, `${pkg.revisionId}/${entry.id}/input`, true);
        checkValue(entry.outputType, `${pkg.revisionId}/${entry.id}/output`, true);
      }
  for (const attachment of attachments)
    if (attachment.kind === "state" && attachment.storagePolicy.kind === "crdt-document")
      checkValue(attachment.valueType, attachment.id);
  const operationMap = new Map<string, PlannedOperation>();
  const queries = linkQueries(workspace);
  const queryKey = (pkg: string, id: string) => JSON.stringify([pkg, id]);
  const queryMap = new Map(queries.map((q) => [queryKey(q.packageRevisionId, q.checked.declaration.id), q]));
  const declaration = (iface: InterfaceRevisionId, operation: OperationId) =>
    interfaces
      .get(iface)
      ?.members.flatMap((m) => m.operations)
      .find((o) => o.id === operation);
  const queryOperations = (query: LinkedQuery) =>
    query.fields.map((f) => publicOperationKey(f.atomId, f.interfaceRevisionId, f.getter));
  const targetAtoms = (binding: DependencyBinding, atom: AtomId): AtomId[] => {
    if (binding.kind === "interface" && binding.receiver === "input")
      return workspace.atoms
        .filter((candidate) =>
          workspace.conformances.some(
            (conformance) =>
              conformance.atomId === candidate.id && conformance.interfaceRevisionId === binding.interfaceRevisionId,
          ),
        )
        .map((candidate) => candidate.id);
    if (!("via" in binding) || !binding.via) return [atom];
    const edge = attachments.find((a) => a.id === binding.via!.edgeTypeId);
    if (!edge || edge.kind !== "edge") throw new ExecutionPlanError("MISSING_EDGE", atom, "Missing traversal edge");
    const endpoint = edge.endpoints.find((e) => e.projectionId !== binding.via!.projectionId)!;
    const constraint = endpoint.constraint;
    return workspace.atoms
      .filter((a) =>
        constraint.kind === "atom"
          ? constraint.atomId === a.id
          : workspace.conformances.some(
              (c) => c.atomId === a.id && c.interfaceRevisionId === constraint.interfaceRevisionId,
            ),
      )
      .map((a) => a.id);
  };
  const add = (atom: AtomId, iface: InterfaceRevisionId, operation: OperationId): PlannedOperation => {
    const key = publicOperationKey(atom, iface, operation),
      existing = operationMap.get(key);
    if (existing) return existing;
    const publicContract = declaration(iface, operation);
    if (!publicContract) throw new ExecutionPlanError("MISSING_OPERATION", key, "Missing public contract");
    const { binding } = resolveForwardedBinding(workspace, atom, iface, operation);
    const planned: PlannedOperation = {
      key,
      atomId: atom,
      interfaceRevisionId: iface,
      operationId: operation,
      scope: publicContract.scope === "class" ? "class" : "object",
      execution: publicContract.execution ?? { kind: "remote" },
      availableTargets: [],
      input: publicContract.inputType,
      output: publicContract.outputType,
      binding,
      dependencies: [],
    };
    operationMap.set(key, planned);
    const portable = planned.execution.kind !== "remote";
    if (portable) {
      checkValue(planned.input, `${key}/input`, true);
      checkValue(planned.output, `${key}/output`, true);
    }
    if (binding.kind === "state" || binding.kind === "journal" || binding.kind === "subscription")
      planned.dependencies.push({ kind: "state", slot: binding.slotId });
    else if (binding.kind === "edge")
      planned.dependencies.push({ kind: "edge", edge: binding.edgeTypeId, projection: binding.projectionId });
    else if (binding.kind === "package") {
      const entry = packages.get(binding.packageRevisionId)?.exports.find((e) => e.id === binding.exportId);
      if (!entry) throw new ExecutionPlanError("MISSING_EXPORT", key, "Unresolved package export");
      for (const dependency of binding.dependencies) {
        const port = entry.dependencyPorts.find((p) => p.id === dependency.portId)!;
        const target = dependency.binding;
        const via = "via" in target && target.via ? { via: target.via } : {};
        if ("via" in target && target.via)
          planned.dependencies.push({ kind: "edge", edge: target.via.edgeTypeId, projection: target.via.projectionId });
        if (target.kind === "state") planned.dependencies.push({ kind: "state", slot: target.slotId, ...via });
        else if (target.kind === "edge")
          planned.dependencies.push({ kind: "edge", edge: target.edgeTypeId, projection: target.projectionId, ...via });
        else if (target.kind === "interface" && port.requirement.kind === "interface") {
          const selected =
            port.requirement.operations ??
            interfaces.get(target.interfaceRevisionId)!.members.flatMap((m) => m.operations.map((o) => o.id));
          for (const targetAtom of targetAtoms(target, atom))
            for (const selectedOperation of selected) {
              const operation = add(targetAtom, target.interfaceRevisionId, selectedOperation);
              planned.dependencies.push({ kind: "operation", operation: operation.key, port: port.id, ...via });
            }
        } else if (target.kind === "query") {
          const query = queryMap.get(queryKey(target.packageRevisionId, target.queryId));
          if (!query) throw new ExecutionPlanError("MISSING_QUERY", key, `Unresolved query port ${port.id}`);
          planned.dependencies.push({
            kind: "query",
            query: queryKey(target.packageRevisionId, target.queryId),
            port: port.id,
          });
        }
      }
    }
    planned.dependencies = sorted(planned.dependencies, canonicalJson);
    return planned;
  };
  for (const conformance of workspace.conformances)
    for (const entry of conformance.operationBindings)
      add(conformance.atomId, conformance.interfaceRevisionId, entry.operationId);
  // Check the transitive closure, retaining a dependency path for diagnostics.
  for (const root of operationMap.values()) {
    if (root.execution.kind === "remote") continue;
    const requested = root.execution,
      visited = new Set<string>();
    const walk = (key: string, path: string[]) => {
      if (visited.has(key)) return;
      visited.add(key);
      const node = operationMap.get(key)!;
      if (node.execution.kind === "remote" || (requested.kind === "snapshot" && node.execution.kind !== "snapshot"))
        throw new ExecutionPlanError(
          "NONPORTABLE_DEPENDENCY",
          path.join(" -> "),
          "Execution effect is not allowed by the root contract",
        );
      for (const dependency of node.dependencies) {
        if (dependency.kind === "operation")
          walk(dependency.operation, [...path, dependency.port, dependency.operation]);
        if (dependency.kind === "query") {
          // An admitted presentation window is not an authoritative mutation read set.
          if (requested.kind === "transaction")
            throw new ExecutionPlanError(
              "QUERY_IN_TRANSACTION",
              [...path, dependency.port].join(" -> "),
              "Capture explicit object references as mutation inputs; local presentation queries cannot define transaction membership",
            );
          const query = queryMap.get(dependency.query)!;
          if (query.checked.declaration.placement?.kind !== "local")
            throw new ExecutionPlanError(
              "REMOTE_QUERY_DEPENDENCY",
              path.join(" -> "),
              "Portable code requires a local query",
            );
          for (const operation of queryOperations(query)) walk(operation, [...path, dependency.port, operation]);
        }
      }
    };
    walk(root.key, [root.key]);
  }
  // Additional implementation targets are opportunities, not new public requirements.
  // Start with provider support and remove targets until the complete installed
  // dependency closure agrees. This also handles recursive call graphs without
  // mistaking an unfinished DFS for proof of availability.
  for (const node of operationMap.values()) {
    if (node.execution.kind === "remote") continue;
    const binding = node.binding;
    const provider =
      binding.kind === "package"
        ? packages.get(binding.packageRevisionId)!.exports.find((entry) => entry.id === binding.exportId)!.execution
        : {
            kind: node.execution.kind,
            targets: backends.filter((backend) => backend.supports(binding)).map((backend) => backend.target),
          };
    if (provider && provider.kind !== "remote") node.availableTargets = [...provider.targets].sort();
  }
  let targetsChanged = true;
  while (targetsChanged) {
    targetsChanged = false;
    for (const node of operationMap.values()) {
      const available = node.availableTargets.filter((target) =>
        node.dependencies.every((dependency) => {
          if (dependency.kind === "operation")
            return operationMap.get(dependency.operation)!.availableTargets.includes(target);
          if (dependency.kind === "query") {
            const query = queryMap.get(dependency.query)!;
            return (
              node.execution.kind === "snapshot" &&
              query.checked.declaration.placement?.kind === "local" &&
              queryOperations(query).every((key) => operationMap.get(key)!.availableTargets.includes(target))
            );
          }
          return true;
        }),
      );
      if (available.length !== node.availableTargets.length) {
        node.availableTargets = available;
        targetsChanged = true;
      }
    }
  }
  for (const node of operationMap.values())
    if (node.execution.kind !== "remote" && !node.availableTargets.includes("server"))
      throw new ExecutionPlanError(
        "MISSING_SERVER_IMPLEMENTATION",
        node.key,
        "Every graph operation requires an authoritative implementation across its dependency closure",
      );
  const plannedQueries: PlannedQuery[] = queries.map((query) => ({
    id: queryKey(query.packageRevisionId, query.checked.declaration.id),
    query,
    operations: queryOperations(query).sort(),
    admittedOperations: [],
  }));
  for (const query of plannedQueries) {
    for (const field of query.query.fields) {
      const operation = operationMap.get(publicOperationKey(field.atomId, field.interfaceRevisionId, field.getter))!;
      const effect = query.query.checked.effects.find(
        (effect) => effect.interfaceRevisionId === field.interfaceRevisionId && effect.memberId === field.memberId,
      );
      if (
        operation.execution.kind === "remote" &&
        (query.query.checked.declaration.placement?.kind === "replica" || effect?.uses.some((use) => use !== "select"))
      )
        throw new ExecutionPlanError(
          "QUERY_REMOTE_MEMBERSHIP_UNSUPPORTED",
          query.id,
          "Remote getters may enrich selected values after native snapshot closure; they cannot determine membership, order or canonical-input admission. Expose an accepted canonical value or split the service result into a separate query.",
        );
      const member = interfaces.get(field.interfaceRevisionId)?.members.find((member) => member.id === field.memberId);
      if (member?.kind === "relationship" && operation.binding.kind !== "edge")
        throw new ExecutionPlanError(
          "QUERY_NON_NATIVE_RELATION",
          query.id,
          "This query runtime traverses native graph edges. Expose an edge relationship, or return a computed service value through a value getter.",
        );
    }
    const unsupported = unsupportedQueryOperator(query.query.checked);
    if (unsupported)
      throw new ExecutionPlanError(
        "QUERY_OPERATOR_UNSUPPORTED",
        query.id,
        `This execution world does not support ${unsupported}. Use a bounded portable getter over admitted inputs, or a server service returning the computed value. Query placement will not change automatically.`,
      );
    const placement = query.query.checked.declaration.placement;
    if (placement?.kind !== "local") continue;
    const source = plannedQueries.find(
      (q) => q.id === queryKey(query.query.packageRevisionId, placement.sourceQueryId),
    );
    if (!source || source.query.checked.declaration.placement?.kind !== "replica")
      throw new ExecutionPlanError("MISSING_REPLICA_SOURCE", query.id, "Local query source must be a replica query");
    const localRoot = query.query.checked.declaration.root,
      sourceRoot = source.query.checked.declaration.root;
    if (localRoot.kind !== sourceRoot.kind || localRoot.interface !== sourceRoot.interface)
      throw new ExecutionPlanError(
        "REPLICA_ROOT_MISMATCH",
        query.id,
        "Local and replica queries must use the same root contract",
      );
    if (localRoot.kind === "workspace-interface") {
      const sourceWindows = source.query.checked.selection
        .flatMap((root) => root.selection)
        .filter((s) => s.name === "objects");
      for (const selection of query.query.checked.selection
        .flatMap((root) => root.selection)
        .filter((s) => s.name === "objects")) {
        if (
          !sourceWindows.some(
            (window) =>
              canonicalJson({ arguments: window.arguments, conditions: window.conditions }) ===
              canonicalJson({ arguments: selection.arguments, conditions: selection.conditions }),
          )
        )
          throw new ExecutionPlanError(
            "REPLICA_WINDOW_MISMATCH",
            query.id,
            "Local objects must observe the identical confirmed source window; use availableObjects for a local candidate view",
          );
      }
    }
    const traversals = (linked: LinkedQuery) => {
      const paths = new Map<string, { complete: boolean; requiresComplete: boolean; windows: Set<string> }>();
      const entry = (key: string) => {
        let value = paths.get(key);
        if (!value) {
          value = { complete: false, requiresComplete: false, windows: new Set() };
          paths.set(key, value);
        }
        return value;
      };
      const visit = (selections: LinkedQuery["checked"]["selection"], parents: string[]) => {
        for (const selection of selections) {
          for (const stage of selection.relational?.stages ?? []) {
            if (stage.operation.kind === "source")
              entry(JSON.stringify([...parents, stage.operation.memberId])).requiresComplete = true;
          }
          const member = selection.interfaceRevisionId
            ? interfaces.get(selection.interfaceRevisionId)?.members.find((m) => m.id === selection.memberId)
            : undefined;
          const path = member?.kind === "relationship" ? [...parents, member.id] : parents;
          if (member?.kind === "relationship") {
            const many = member.cardinality === "many" || member.cardinality === "many-unique";
            const complete = !selection.predicate && (!many || !!selection.arguments.all);
            const key = JSON.stringify(path);
            const value = entry(key);
            value.complete ||= complete;
            if (selection.arguments.first)
              value.windows.add(canonicalJson({ arguments: selection.arguments, conditions: selection.conditions }));
            else value.requiresComplete = true;
          }
          visit(selection.selection, path);
        }
      };
      visit(linked.checked.selection, []);
      return paths;
    };
    const admittedTraversals = traversals(source.query);
    for (const [traversal, needed] of traversals(query.query)) {
      if (!admittedTraversals.has(traversal))
        throw new ExecutionPlanError(
          "REPLICA_TRAVERSAL_MISSING",
          query.id,
          `Replica source does not admit relationship path ${traversal}`,
        );
      if (
        !admittedTraversals.get(traversal)!.complete &&
        (needed.requiresComplete ||
          !needed.windows.size ||
          [...needed.windows].some((window) => !admittedTraversals.get(traversal)!.windows.has(window)))
      )
        throw new ExecutionPlanError(
          "REPLICA_RELATION_INCOMPLETE",
          query.id,
          `Local relationship ${traversal} needs either complete source candidates or the identical confirmed first window; a window cannot supply unseen matches`,
        );
    }
    // The admission executor follows these canonical dependencies on the admitted roots.
    // They do not change source candidate membership or make local take/filters authoritative.
    source.admittedOperations.push(...query.operations);
    for (const operation of query.operations) {
      const node = operationMap.get(operation)!;
      if (node.execution.kind !== "snapshot" || !node.availableTargets.some((target) => target !== "server"))
        throw new ExecutionPlanError(
          "NONPORTABLE_QUERY_FIELD",
          `${query.id}/${operation}`,
          "Local query getter needs an installed local snapshot implementation",
        );
    }
  }
  for (const query of plannedQueries) query.admittedOperations = [...new Set(query.admittedOperations)].sort();
  const schema: BindingSchema = {
    format: "quixos-bindings",
    version: 1,
    interfaces: sorted(
      workspace.interfaceImports.filter((i) => !i.template),
      (i) => i.revisionId,
    ),
    interfaceTemplates: sorted(
      workspace.interfaceImports.filter((i) => i.template),
      (i) => i.revisionId,
    ),
    packages: sorted(workspace.packageImports, (p) => p.revisionId),
  };
  const normalizedSchema = JSON.parse(canonicalJson(schema)) as BindingSchema;
  const buildContexts = packageBuildContexts(normalizedSchema);
  const definition: ExecutionPlanDefinition = {
    codec: "camino-execution-plan-v1",
    workspace,
    bindingSchema: normalizedSchema,
    ...(workspace.presentations?.length ? { presentations: sorted(workspace.presentations, (p) => p.id) } : {}),
    packages: sorted(workspace.packageImports, (p) => p.revisionId).map((p) => {
      const contract = buildContexts[p.revisionId]!.contract;
      return {
        ...contract.definition.package,
        source: p.source,
        sourceDigest: hexDigest({ revision: p.revisionId, source: p.source }),
        bindingDigest: contract.digest,
      };
    }),
    owners: sorted(workspace.conformances, (c) => c.id ?? "").map((c) => {
      if (!c.id)
        throw new ExecutionPlanError(
          "OWNER_ID_REQUIRED",
          `${c.atomId}/${c.interfaceRevisionId}`,
          "Installed state owners require explicit stable identities",
        );
      return {
        id: c.id,
        atom: c.atomId,
        interface: c.interfaceRevisionId,
        initialization: c.initialization ?? [],
        storage: c.privateAttachments,
      };
    }),
    operations: sorted([...operationMap.values()], (o) => o.key),
    queries: sorted(plannedQueries, (q) => q.id),
    profiles: sorted(
      attachments.filter((a) => a.kind === "state" && a.storagePolicy.kind === "crdt-document"),
      (a) => a.id,
    ).map((a) => ({ slot: a.id, profile: "camino-automerge-3.4.1-structured-v1" })),
    versions: { ...executionVersions },
  };
  const normalized = JSON.parse(canonicalJson(definition)) as ExecutionPlanDefinition;
  return { definition: normalized, digest: hexDigest(normalized) };
}