import fs from "node:fs/promises";
import path from "node:path";
import os from "node:os";
import {randomUUID} from "node:crypto";
import {execFile as callback} from "node:child_process";
import {promisify} from "node:util";
import {loadQuixosLock, parseQuixosLockDocument} from "../resource-lock/index.js";
import {contentDigest} from "../capability-model/evolution.js";
import {planStructure, applyStructure, type StructuralRequest} from "./structural-plan.js";
import {snapshotRepository} from "./candidate-check.js";
import {compileWorkspaceRepository, compileCapabilityResourceRepository, type ResolvedCapabilityResource} from "./assembly.js";
import {createGitCapabilityResolver} from "./git-resolver.js";
import {snapshotCommit, buildImmutableCandidate} from "./checked-build.js";
import {planEvolution, type WorkspaceRevision, type EvolutionReview} from "../capability-model/index.js";
import {withFileLock} from "./file-lock.js";
const execFile = promisify(callback);
type Source = {repository: string; commit: string};
export type UpgradeNode = {kind: "workspace" | "package" | "interface"; directory: string; source: Source};
export type UpgradeSpec = {nodes: UpgradeNode[]; quixos?: Source; baseline?: string; reviews?: string; bootstrap?: boolean};
type NodePlan = UpgradeNode & {treeDigest: string; dependencies: string[]; lockFiles: string[]};
export type UpgradePlan = {schemaVersion: 1; workbench: string; spec: UpgradeSpec; nodes: NodePlan[]; digest: string};
type Step = {directory: string; phase: "editing" | "prepared" | "refactor" | "checked" | "publishing" | "published"; commit?: string; treeDigest?: string; structuralJournal?: string; structuralPlan?: Awaited<ReturnType<typeof planStructure>>};
type Journal = {schemaVersion: 1; plan: UpgradePlan; steps: Step[]};
const sourceKey = (node: {kind: string; source: Source}) => JSON.stringify([node.kind, node.source.repository, node.source.commit]);
const command = async (cwd: string, tool: string, args: string[]) => (await execFile(tool, args, {cwd, maxBuffer: 16 * 1024 * 1024, env: {...process.env, GIT_TERMINAL_PROMPT: "0", QUIXOS_JJ_NO_CHECKPOINT: "1", QUIXOS_SUBTREE_PUBLISH: "0"}})).stdout.trim();
const validSource = (value: Source) => {
  const url = new URL(value.repository);
  if (url.protocol !== "https:" || url.username || url.password || url.search || url.hash || !/^(?:[a-f0-9]{40}|[a-f0-9]{64})$/.test(value.commit)) throw new Error("Upgrade sources must be exact credential-free HTTPS revisions");
};
const location = async (root: string, directory: string) => {
  if (directory !== "root" && !/^resources\/[A-Za-z0-9][A-Za-z0-9._-]*$/.test(directory)) throw new Error("Upgrade target must be a managed root/resource repository");
  const resolved = await fs.realpath(path.join(root, directory));
  if (resolved !== path.join(root, directory)) throw new Error("Upgrade target crosses a symlink");
  return resolved;
};
const treeDigest = async (root: string) => {
  const temporary = await fs.mkdtemp(path.join(os.tmpdir(), "qx-upgrade-tree-"));
  try {return (await snapshotRepository(root, temporary)).treeDigest;} finally {await fs.rm(temporary, {recursive: true, force: true});}
};
const writeJournal = async (filename: string, journal: unknown) => {
  const temp = `${filename}.${randomUUID()}.tmp`;
  const handle = await fs.open(temp, "wx", 0o600);
  try {await handle.writeFile(JSON.stringify(journal, null, 2)); await handle.sync();} finally {await handle.close();}
  await fs.rename(temp, filename);
  const directory = await fs.open(path.dirname(filename), "r");
  try {await directory.sync();} finally {await directory.close();}
};

export const discoverUpgradeSpec = async (workbench: string): Promise<UpgradeSpec> => {
  const graph = JSON.parse(await fs.readFile(path.join(workbench, ".quixos/resource-graph.json"), "utf8"));
  const root = await location(workbench, "root");
  const nodes: UpgradeNode[] = [{kind: "workspace", directory: "root", source: {
    repository: await command(root, "git", ["config", "--get", "remote.origin.url"]),
    commit: await command(root, "jj", ["--ignore-working-copy", "log", "--no-graph", "-r", "@", "-T", "commit_id"]),
  }}, ...graph.resources.map((entry: {kind: "interface" | "package"; directory: string; source: Source}) => ({kind: entry.kind, source: entry.source,
    directory: path.relative(workbench, path.resolve(workbench, entry.directory))}))];
  let baseline: string | undefined;
  try {
    const host = JSON.parse(await fs.readFile("/etc/quixos/workspace-source.json", "utf8"));
    if (await fs.realpath(host.workbenchRoot) === await fs.realpath(workbench)) baseline = JSON.parse(await fs.readFile(path.join(host.runtimeClosureRoot, "manifest.json"), "utf8")).workspacePlanPath;
  } catch (error) {if (!["ENOENT", "EACCES"].includes((error as NodeJS.ErrnoException).code ?? "")) throw error;}
  return {nodes, baseline};
};

/** Read-only source plan. Repositories are selected explicitly, including any
 * parallel versions of the same resource; no guesses at a floating 'latest'. */
export const planPinUpgrades = async (workbenchPath: string, spec: UpgradeSpec): Promise<UpgradePlan> => {
  const workbench = await fs.realpath(workbenchPath);
  if (!Array.isArray(spec.nodes) || !spec.nodes.length || spec.nodes.length > 100 || spec.nodes.filter((node) => node.kind === "workspace").length !== 1) throw new Error("Upgrade graph requires one workspace and at most 100 repositories");
  if (spec.quixos) validSource(spec.quixos);
  const keys = new Map<string, string>();
  for (const node of spec.nodes) {
    validSource(node.source);
    if (!["workspace", "package", "interface"].includes(node.kind) || keys.has(sourceKey(node))) throw new Error("Duplicate/invalid upgrade resource identity");
    keys.set(sourceKey(node), node.directory);
  }
  if (new Set(spec.nodes.map((node) => node.directory)).size !== spec.nodes.length) throw new Error("Upgrade directories must be distinct");
  const nodes: NodePlan[] = [];
  for (const node of spec.nodes) {
    const root = await location(workbench, node.directory);
    if (await command(root, "git", ["config", "--get", "remote.origin.url"]) !== node.source.repository) throw new Error(`Upgrade origin differs from selected source: ${node.directory}`);
    const loaded = await loadQuixosLock(path.join(root, "quixos.lock"));
    if (!loaded.ok) throw new Error(`Invalid lock in ${node.directory}: ${loaded.diagnostics.map((entry) => entry.message).join("; ")}`);
    const dependencies = loaded.lock.resources.map((resource) => keys.get(sourceKey(resource))).filter((value): value is string => Boolean(value));
    nodes.push({...node, treeDigest: await treeDigest(root), dependencies: [...new Set(dependencies)], lockFiles: loaded.lock.sourceFiles ?? ["quixos.lock"]});
  }
  const ordered: NodePlan[] = [], remaining = [...nodes];
  while (remaining.length) {
    const index = remaining.findIndex((node) => node.dependencies.every((dependency) => ordered.some((entry) => entry.directory === dependency)));
    if (index < 0) throw new Error("Cyclic source publication graph");
    ordered.push(remaining.splice(index, 1)[0]);
  }
  const workspace = ordered.find((node) => node.kind === "workspace")!;
  // Even unreferenced new resources are published before the root.
  ordered.splice(ordered.indexOf(workspace), 1); ordered.push(workspace);
  const plan = {schemaVersion: 1 as const, workbench, spec, nodes: ordered};
  return {...plan, digest: contentDigest(plan)};
};

export type UpgradeEffects = {
  check(node: NodePlan, root: string, output: string, spec: UpgradeSpec): Promise<void>;
  snapshot(root: string): Promise<string>;
  publish(root: string, commit: string): Promise<void>;
};
const effects: UpgradeEffects = {
  async check(node, root, output, spec) {
    if (node.kind === "workspace" && !spec.baseline && !spec.bootstrap) throw new Error("Upgrading a workspace requires its checked active baseline for major-review checks (or explicit bootstrap:true for a new workspace)");
    // Explicit baseline upgrades use the same immutable Nix checker. Retaining
    // an unverified source is safe and must precede a remote flake fetch.
    await fs.mkdir(output);
    const commit = await snapshotCommit(root);
    await effects.publish(root, commit);
    const artifact = await buildImmutableCandidate({...node.source, commit}, node.kind, path.join(output, "nix.log"));
    const candidate = await fs.readFile(path.join(artifact, "candidate.json"), "utf8");
    await fs.writeFile(path.join(output, "candidate.json"), candidate);
    if (node.kind === "workspace") {
      const baseline = spec.baseline ? JSON.parse(await fs.readFile(spec.baseline, "utf8")) as WorkspaceRevision : null;
      const reviews = spec.reviews ? JSON.parse(await fs.readFile(spec.reviews, "utf8")) as EvolutionReview[] : [];
      const evolution = planEvolution(baseline, JSON.parse(candidate), {reviews});
      await fs.writeFile(path.join(output, "evolution.json"), JSON.stringify(evolution, null, 2));
      if (evolution.blockers.length) throw new Error(`Refactor required in ${node.directory}: ${evolution.blockers.join("; ")}`);
    }
  },
  async snapshot(root) {
    const commit = await snapshotCommit(root);
    if (!/^(?:[a-f0-9]{40}|[a-f0-9]{64})$/.test(commit)) throw new Error("Publication did not resolve an exact commit");
    await command(root, "git", ["diff", "--exit-code", "--no-ext-diff", "--no-textconv", commit, "--"]);
    const tracked = new Set((await command(root, "git", ["ls-tree", "-r", "--name-only", "-z", commit])).split("\0"));
    for (const file of (await command(root, "git", ["ls-files", "--others", "--exclude-standard", "-z"])).split("\0").filter(Boolean)) if (!tracked.has(file)) throw new Error(`Uncaptured source file ${file}`);
    return commit;
  },
  async publish(root, commit) {
    const ref = `refs/tags/quixos-reachability/${commit}`;
    const remote = await command(root, "git", ["ls-remote", "--refs", "origin", ref]);
    if (remote && remote !== `${commit}\t${ref}`) throw new Error("Immutable publication ref conflict");
    if (!remote) await command(root, "git", ["push", "origin", `${commit}:${ref}`]);
    if (await command(root, "git", ["ls-remote", "--refs", "origin", ref]) !== `${commit}\t${ref}`) throw new Error("Publication response uncertain; retry the same journal");
  },
};

/** Explicit --publish only. Append-only remote retention; never moves the
 * workspace branch, activates code, or rolls back previously published nodes. */
export const applyPinUpgrades = async (plan: UpgradePlan, journalId?: string, implementation: UpgradeEffects = effects, options: {acceptEdits?: boolean} = {}) => {
  if (implementation === effects && !plan.spec.baseline && !plan.spec.bootstrap) throw new Error("Publication requires an active checked baseline or explicit bootstrap:true");
  const {digest, ...body} = plan;
  if (contentDigest(body) !== digest) throw new Error("Upgrade plan digest mismatch");
  const directory = path.join(plan.workbench, ".quixos", "upgrades");
  await fs.mkdir(directory, {recursive: true, mode: 0o700});
  if (await fs.realpath(directory) !== directory) throw new Error("Upgrade journals must not cross symlinks");
  const id = journalId ?? randomUUID();
  if (!/^[a-f0-9-]{36}$/.test(id)) throw new Error("Invalid upgrade journal ID");
  const filename = path.join(directory, `${id}.json`);
  return withFileLock(path.join(directory, "writer.lock"), async () => {
  try {
    const journal: Journal = journalId ? JSON.parse(await fs.readFile(filename, "utf8")) : {schemaVersion: 1, plan, steps: []};
    if (journal.plan.digest !== plan.digest) throw new Error("Upgrade journal belongs to another plan");
    if (!journalId) await writeJournal(filename, journal);
    for (const node of plan.nodes) {
      const root = await location(plan.workbench, node.directory);
      if (await command(root, "git", ["config", "--get", "remote.origin.url"]) !== node.source.repository) throw new Error("Upgrade remote changed after planning");
      let step = journal.steps.find((entry) => entry.directory === node.directory);
      if (step?.phase === "published") continue;
      if (!step) {
        if (await treeDigest(root) !== node.treeDigest) throw new Error(`Stale upgrade plan: ${node.directory}`);
        const files: StructuralRequest["files"] = [];
        for (const file of node.lockFiles) {
          const parsed = parseQuixosLockDocument(await fs.readFile(path.join(root, file), "utf8"));
          if (!parsed.ok) throw new Error("Invalid lock during upgrade");
          const edits = [];
          for (const resource of parsed.document.resources) {
            const dependency = plan.nodes.find((entry) => sourceKey(entry) === sourceKey(resource));
            const published = dependency && journal.steps.find((entry) => entry.directory === dependency.directory && entry.phase === "published");
            if (published?.commit && published.commit !== resource.source.commit) edits.push({operation: "dependency" as const, kind: resource.kind, name: resource.binding, source: {...resource.source, commit: published.commit}});
          }
          if (parsed.document.kind === "root" && plan.spec.quixos) edits.push({operation: "quixos-pin" as const, source: plan.spec.quixos});
          if (edits.length) files.push({file, edits});
        }
        const structuralPlan = files.length ? await planStructure(root, {kind: node.kind, source: node.source, files}, process.env.QUIXOS_SNAPSHOT_MAP) : undefined;
        step = {directory: node.directory, phase: "editing", treeDigest: node.treeDigest, structuralPlan, structuralJournal: structuralPlan ? randomUUID() : undefined};
        journal.steps.push(step); await writeJournal(filename, journal);
      }
      if (step.phase === "editing") {
        if (step.structuralPlan) await applyStructure(step.structuralPlan, step.structuralJournal);
        else if (await treeDigest(root) !== step.treeDigest) throw new Error("Source changed before upgrade editing");
        step.treeDigest = await treeDigest(root);
        step.phase = "prepared";
        await writeJournal(filename, journal);
      }
      if (step.phase === "refactor") {
        const current = await treeDigest(root);
        if (current !== step.treeDigest && !options.acceptEdits) throw new Error("Refactored source requires --accept-edits when resuming");
        step.treeDigest = current; step.phase = "prepared"; await writeJournal(filename, journal);
      }
      if (await treeDigest(root) !== step.treeDigest) throw new Error(`Source changed during upgrade: ${node.directory}; inspect ${filename}`);
      if (step.phase === "prepared") {
        try {await implementation.check(node, root, path.join(directory, `${id}-${node.directory.replaceAll("/", "-")}-${randomUUID()}`), plan.spec);}
        catch (error) {step.phase = "refactor"; await writeJournal(filename, journal); throw error;}
        if (await treeDigest(root) !== step.treeDigest) throw new Error("Source changed while checking");
        step.phase = "checked"; await writeJournal(filename, journal);
      }
      if (step.phase === "checked") {
        step.commit = await implementation.snapshot(root);
        if (await treeDigest(root) !== step.treeDigest) throw new Error("Publication snapshot changed checked files");
        step.phase = "publishing"; await writeJournal(filename, journal);
      }
      await implementation.publish(root, step.commit!);
      step.phase = "published"; await writeJournal(filename, journal);
    }
    // Keep subsequent automatic upgrades associated with the newly published
    // identities, without renaming repositories or changing any selected branch.
    // Explicit-spec callers without a managed graph retain the journal as their
    // source of revisions instead.
    const graphFile = path.join(plan.workbench, ".quixos/resource-graph.json");
    let graphText: string | undefined;
    try {graphText = await fs.readFile(graphFile, "utf8");} catch (error) {if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;}
    if (graphText !== undefined) {
      const previous = JSON.parse(graphText);
      const snapshots = await Promise.all(previous.resources.map(async (entry: {kind: string; source: Source; directory: string}) => ({kind: entry.kind, ...entry.source, directory: await location(plan.workbench, path.relative(plan.workbench, path.resolve(plan.workbench, entry.directory)))})));
      for (const node of plan.nodes.filter((entry) => entry.kind !== "workspace")) {
        const step = journal.steps.find((entry) => entry.directory === node.directory)!;
        if (await treeDigest(await location(plan.workbench, node.directory)) !== step.treeDigest) throw new Error("Published source changed before workbench graph refresh");
        snapshots.push({kind: node.kind, repository: node.source.repository, commit: step.commit, directory: path.join(plan.workbench, node.directory)});
      }
      const unique = [...new Map(snapshots.map((entry: {kind: string; repository: string; commit: string}) => [JSON.stringify([entry.kind, entry.repository, entry.commit]), entry])).values()];
      const snapshotMap = path.join(directory, `${id}-published-snapshots.json`);
      await fs.writeFile(snapshotMap, JSON.stringify({resources: unique}));
      const resolveResource = await createGitCapabilityResolver({checkoutRoot: path.join(directory, `${id}-graph-resources`), snapshotMap, snapshotOnly: true});
      const rootNode = plan.nodes.find((node) => node.kind === "workspace")!;
      if (await treeDigest(await location(plan.workbench, rootNode.directory)) !== journal.steps.find((step) => step.directory === rootNode.directory)!.treeDigest) throw new Error("Root source changed before workbench graph refresh");
      const compiled = await compileWorkspaceRepository({rootDirectory: await location(plan.workbench, rootNode.directory), resolveResource});
      // Managed repositories need not currently be reachable from the workspace.
      // Keep them discoverable/checkpointed until explicitly removed by the user.
      const resources = new Map<string, ResolvedCapabilityResource>(compiled.resources.map((node) => [node.key, node]));
      for (const node of plan.nodes.filter((entry) => entry.kind !== "workspace")) {
        const step = journal.steps.find((entry) => entry.directory === node.directory)!;
        const source = {resolver: "git" as const, repository: node.source.repository, commit: step.commit!};
        const key = `${node.kind}\0${source.repository}\0${source.commit}`;
        if (resources.has(key)) continue;
        const directory = await location(plan.workbench, node.directory);
        const standalone = await compileCapabilityResourceRepository({rootDirectory: directory, kind: node.kind as "package" | "interface", source, resolveResource});
        for (const dependency of standalone.resources) resources.set(dependency.key, dependency);
        resources.set(key, {key, kind: node.kind as "package" | "interface", source, directory, lock: standalone.lock, resource: standalone.resource, dependencies: standalone.directResources});
      }
      await writeJournal(graphFile, {formatVersion: 1, quixos: compiled.lock.quixos,
        directResources: [...compiled.directResources.entries()].map(([bindingKey, node]) => {const [kind, binding] = bindingKey.split("\0"); return {kind, binding, resourceKey: node.key, directory: node.directory};}),
        resources: [...resources.values()].map((node) => ({key: node.key, kind: node.kind, source: node.source, directory: node.directory,
          resourceId: node.resource.kind === "interface" ? node.resource.revision.interfaceId : node.resource.revision.packageId,
          revisionId: node.resource.revision.revisionId, dependencies: [...node.dependencies.entries()].map(([binding, dependency]) => ({binding, resourceKey: dependency.key}))})),
      });
    }
    return {id, journal: filename, revisions: journal.steps.map((step) => ({directory: step.directory, commit: step.commit})), activated: false};
  } catch (error) {throw new Error(`${error instanceof Error ? error.message : String(error)}; upgrade journal ${filename}`, {cause: error});}
  });
};