import { BadRequestException, ForbiddenException, Injectable } from '@nestjs/common';
import { DEFAULT_ATTACHMENT_EXTENSIONS, VS_NFD_PROFILE, isVsNfdCompliant } from '@dorfteich/shared';
import { Prisma } from '@prisma/client';
import { PinoLogger } from 'nestjs-pino';
import { z } from 'zod';

import { AuditService } from '../audit/audit.service';
import { AppConfig } from '../config/app-config.service';
import { PrismaService } from '../prisma/prisma.service';

/**
 * The typed registry of instance settings. Adding a setting = adding a
 * line here; readers get parsed, defaulted values and writers get
 * validation for free. Secrets never go through this table
 * (security.md §Secrets).
 */
export const INSTANCE_SETTINGS = {
  'auth.registrationMode': z.enum(['open', 'closed']).default('open'),
  'instance.name': z.string().trim().min(1).max(60).default('Dorfteich'),
  'instance.defaultLocale': z.enum(['de', 'en']).default('en'),
  // Instance-default quotas (ADR 0011); per-user/per-pond overrides live
  // in quota_overrides and win over these (QuotaService, issue #22).
  'quota.editorsPerPond': z.number().int().min(0).default(5),
  'quota.readersPerPond': z.number().int().min(0).default(50),
  'quota.additionalPonds': z.number().int().min(0).default(0),
  'quota.storageBytes': z
    .number()
    .int()
    .min(0)
    .default(1024 * 1024 * 1024),
  'quota.maxFileBytes': z
    .number()
    .int()
    .min(0)
    .default(25 * 1024 * 1024),
  // Trash retention (ADR 0013, issue #31): days a soft-deleted page stays
  // restorable before the daily purge job removes it for good.
  'trash.retentionDays': z.number().int().min(1).default(30),
  // Audit-trail retention (issue #196): days an `audit_log` entry is kept
  // before the daily retention job removes it; the deletion itself is
  // recorded (`audit.pruned`) so the gap is explainable. The read-access
  // trail (#224) is deliberately NOT covered — it gets its own period.
  'audit.retentionDays': z.number().int().min(1).default(365),
  // Conversion-job payload retention (issue #233): days a finished
  // (succeeded/failed) import/export job keeps its raw input/result bytes
  // before the daily prune job nulls them. The row itself survives for
  // status/audit purposes; PENDING/RUNNING jobs are never touched.
  'conversion.payloadRetentionDays': z.number().int().min(1).default(30),
  // Mail outbox retention (issue #234): days a SENT or permanently FAILED
  // outbox row is kept before the daily retention job deletes it. Digest
  // bodies carry page titles (content-adjacent data), so the copy must be
  // bounded. PENDING rows — including failed-but-retryable ones — are
  // never touched; the retry loop owns them.
  'mail.outboxRetentionDays': z.number().int().min(1).default(30),
  // IdP claim mapping (issue #217, ADR 0021): declarative rules turning
  // ID-token claims into pond roles and the site-admin flag — instance
  // configuration, not code. Applied on every OIDC login through the same
  // grant service path as manual grants (cache + collab revocation stay
  // correct); the mapping only creates/revokes rows it owns (origin `idp`)
  // and only demotes a site admin it itself promoted. `site_admin` rules
  // take no pond; every other role requires one.
  'idpMapping.rules': z
    .array(
      z.object({
        claim: z.string().min(1),
        value: z.string().min(1),
        role: z.enum(['site_admin', 'pond_admin', 'editor', 'reader']),
        pondSlug: z.string().min(1).optional(),
      }),
    )
    .superRefine((rules, ctx) => {
      rules.forEach((rule, index) => {
        if (rule.role === 'site_admin' && rule.pondSlug) {
          ctx.addIssue({ code: 'custom', path: [index], message: 'validation.invalid' });
        }
        if (rule.role !== 'site_admin' && !rule.pondSlug) {
          ctx.addIssue({ code: 'custom', path: [index], message: 'validation.required' });
        }
      });
    })
    .default([]),
  // Read-trail master switch (issue #225, ADR 0023). Default OFF: read
  // logging is employee monitoring in a works council's eyes — an ordinary
  // instance must not surveil reads. The VS-NfD reference configuration
  // (#227) turns it on together with the written purpose limitation
  // (60-sicherheitsdokumentation.md §7). Off means NO event is written
  // anywhere, including stdout; the api states the switch position once at
  // startup, so a gap in the evidence is never ambiguous.
  'readTrail.enabled': z.boolean().default(false),
  // Read-trail dedup window (issue #223, ADR 0023): one event per
  // (session, page, channel) within an aligned window of this many minutes.
  // 5 minutes keeps a live Yjs session (collab tokens every 60 s) at a
  // bounded ~12 events/hour/page while still evidencing distinct visits.
  'readTrail.dedupWindowMinutes': z.number().int().min(1).default(5),
  // Read-trail retention (issue #224): days a read event is kept before the
  // daily maintenance job removes it — deliberately independent of
  // `audit.retentionDays` (#196), because volume, purpose and legal basis
  // differ. The deletion itself is audited (`read_trail.pruned`), so a gap
  // is always explainable. One year mirrors the audit default; shortening
  // it is an operator decision under the purpose limitation (#225).
  'readTrail.retentionDays': z.number().int().min(1).default(365),
  // Default VS-NfD classification for newly created pages (ADR 0022,
  // issue #204). An instance operated inside a classified environment sets
  // this to `vs_nfd` so nothing starts unmarked; inheritance from the
  // parent page (#205) wins over this default. The marking is not a
  // protection mechanism — permissions ignore it.
  'classification.newPageDefault': z.enum(['unclassified', 'vs_nfd']).default('unclassified'),
  // Attaching files to a classified page (issue #213, ADR 0022): the UI
  // always warns (the file inherits a classification its content cannot
  // carry, #212); `block` hardens the warning into a server-side rejection.
  // Default `warn` — blocking is the reference-configuration choice (#227).
  'classification.uploadPolicy': z.enum(['warn', 'block']).default('warn'),
  // Non-image upload allowlist (ADR 0011, issue #61): lowercase extensions
  // without the dot. Images are always allowed regardless; SVG is governed
  // by `upload.svgPolicy`. Normalized (lowercased, dot-stripped, deduped) so
  // an admin can paste `.PDF` or `pdf` interchangeably.
  'upload.allowedExtensions': z
    .array(z.string())
    .transform((exts) => [
      ...new Set(exts.map((e) => e.trim().replace(/^\./, '').toLowerCase()).filter(Boolean)),
    ])
    .pipe(z.array(z.string().regex(/^[a-z0-9]+$/)))
    .default([...DEFAULT_ATTACHMENT_EXTENSIONS]),
  // SVG upload handling (security.md §Uploads): sanitize strips scripts and
  // event handlers with a maintained library; reject refuses SVG outright.
  'upload.svgPolicy': z.enum(['reject', 'sanitize']).default('sanitize'),
  // Public REST API master switch (issue #104, default off): every
  // /api/public/v1 route answers 404 while disabled. Individual ponds
  // additionally opt in through their pond settings (`apiEnabled`).
  'api.enabled': z.boolean().default(false),
  // Built-in MCP endpoint master switch (issue #105, default off) —
  // independent of the REST switch; ponds opt in via `mcpEnabled`.
  'mcp.enabled': z.boolean().default(false),
  // Plugin-architecture master switch (issue #200, ADR 0025). Default ON:
  // plugins predate the switch, so existing instances keep working; the
  // VS-NfD reference configuration (#227) turns it off. While off, every
  // plugin surface answers 404 (admin install/list, pond toggles, frame
  // and asset routes) — only the authenticated fallback-metadata route
  // stays, so existing blocks still render their declared text fallback
  // (an image fallback degrades to neutral text: its bytes live on the
  // disabled asset surface).
  'plugins.enabled': z.boolean().default(true),
  // Plugin allowlist with SHA-256 hash pinning (issue #232, ADR 0025).
  // Empty (the default) = pinning is NOT enforced — plugins load as
  // before, which keeps existing instances working. Non-empty = only the
  // listed plugin ids load, and only while the installed bundle's
  // observed hash equals the pinned one; installs of unlisted or
  // mismatching bundles are rejected, loads fail closed (assets/frame
  // 404, audited `plugin.rejected`). A version bump changes the bundle
  // hash, so it requires an explicit re-pin — the intended friction.
  'plugins.allowlist': z
    .array(
      z.object({
        id: z.string().min(1),
        sha256: z
          .string()
          .trim()
          .toLowerCase()
          .regex(/^[a-f0-9]{64}$/),
      }),
    )
    .default([]),
  // Atom feed master switch (issue #191). Default ON: feeds predate the
  // switch, so existing instances and their subscribed readers keep
  // working; the VS-NfD reference configuration (#227) turns it off.
  // While disabled, the feed routes AND the feed-token management answer
  // 404 (existence hidden, same semantics as the two switches above).
  'feeds.enabled': z.boolean().default(true),
  // Backup targets (ADR 0015, issue #103). The backup sidecar reads these
  // rows directly (apps/backup settings.ts — keep the schemas in sync); the
  // Nextcloud app password is NOT here, it lives in the secret store
  // (security.md §Secrets). localRetentionDays `null` = no admin override,
  // the sidecar's BACKUP_RETENTION_DAYS env stays authoritative.
  'backup.localRetentionDays': z.number().int().min(1).nullable().default(null),
  'backup.remoteRetentionDays': z.number().int().min(1).default(30),
  'backup.nextcloud.enabled': z.boolean().default(false),
  'backup.nextcloud.baseUrl': z.string().trim().url().or(z.literal('')).default(''),
  'backup.nextcloud.username': z.string().trim().max(200).default(''),
  'backup.nextcloud.folder': z
    .string()
    .trim()
    .max(500)
    .refine((folder) => !folder.split('/').some((s) => s === '.' || s === '..'), {
      message: 'validation.invalid',
    })
    .default('dorfteich-backups'),
  'backup.nextcloud.uploadSchedule': z.enum(['off', 'daily', 'weekly']).default('daily'),
  // Instance legal pages (issue #82, security.md §Privacy): Markdown texts
  // for imprint and privacy policy, rendered publicly at /legal/<kind>.
  // Empty = not configured yet (the legal pages then show a notice and
  // Site Admins a warning banner instead of silently missing).
  'legal.imprint': z.string().max(100_000).default(''),
  'legal.privacyPolicy': z.string().max(100_000).default(''),
  // Landing-page body: the Site Admin's Markdown for the public home page
  // (`/`), rendered through the same sanitizing pipeline as the legal pages.
  // Empty = the built-in default welcome text is shown instead.
  'home.content': z.string().max(100_000).default(''),
  // When the first-run setup wizard completed (issue #80). Null = the
  // instance still requires setup and only /setup/* is reachable; once set
  // the wizard is locked for good (SetupStateService). Written by the wizard,
  // env pre-seeding, the fixture seed, and a backfill migration for
  // instances that predate the wizard.
  'setup.completedAt': z.string().nullable().default(null),
} as const;

export type InstanceSettingKey = keyof typeof INSTANCE_SETTINGS;
export type InstanceSettingValue<K extends InstanceSettingKey> = z.infer<
  (typeof INSTANCE_SETTINGS)[K]
>;
export type InstanceSettings = { [K in InstanceSettingKey]: InstanceSettingValue<K> };

/**
 * Typed, cached access to instance_settings. The in-process cache is
 * invalidated on every write; with one api container per stage
 * (ADR 0002) that is sufficient — no cross-instance bus needed yet.
 */
@Injectable()
export class InstanceSettingsService {
  private cache = new Map<InstanceSettingKey, unknown>();

  constructor(
    private readonly prisma: PrismaService,
    private readonly audit: AuditService,
    private readonly logger: PinoLogger,
    private readonly config: AppConfig,
  ) {
    this.logger.setContext(InstanceSettingsService.name);
  }

  async get<K extends InstanceSettingKey>(key: K): Promise<InstanceSettingValue<K>> {
    if (this.cache.has(key)) return this.cache.get(key) as InstanceSettingValue<K>;
    const row = await this.prisma.instanceSetting.findUnique({ where: { key } });
    const parsed = INSTANCE_SETTINGS[key].safeParse(row?.value);
    // Unknown/invalid stored values fall back to the schema default
    // instead of breaking the instance.
    const value = parsed.success ? parsed.data : INSTANCE_SETTINGS[key].parse(undefined);
    this.cache.set(key, value);
    return value as InstanceSettingValue<K>;
  }

  async getAll(): Promise<InstanceSettings> {
    const entries = await Promise.all(
      (Object.keys(INSTANCE_SETTINGS) as InstanceSettingKey[]).map(
        async (key) => [key, await this.get(key)] as const,
      ),
    );
    return Object.fromEntries(entries) as InstanceSettings;
  }

  async set<K extends InstanceSettingKey>(
    key: K,
    value: unknown,
    actorUserId: string,
  ): Promise<InstanceSettingValue<K>> {
    const parsed = INSTANCE_SETTINGS[key].safeParse(value);
    if (!parsed.success) {
      throw new BadRequestException({
        code: 'bad_request',
        details: { [key]: parsed.error.issues.map((i) => i.message) },
      });
    }
    // Mode `enforced` (#246, ADR 0027): a write that would set a
    // catalog-violating value is rejected at the ONE write path every
    // caller uses — hiding alone (#245) is UI cosmetics a scripted client
    // bypasses. Existing violating values are reported (startup log,
    // admin card), never auto-changed: the operator resolves them
    // consciously, and writes that DECREASE compliance are what this
    // blocks. 403, not 400: the request is well-formed, the policy says no.
    if (this.config.env.VS_NFD_MODE === 'enforced') {
      const entry = VS_NFD_PROFILE.find((e) => e.scope === 'instance' && e.key === key);
      if (entry && !isVsNfdCompliant(entry, parsed.data)) {
        throw new ForbiddenException({
          code: 'vs_nfd_profile_violation',
          details: { [key]: ['vs_nfd_profile_violation'] },
        });
      }
    }
    // Nullable settings (setup.completedAt) store JSON null explicitly —
    // Prisma requires the sentinel for that.
    const stored = parsed.data === null ? Prisma.JsonNull : parsed.data;
    await this.prisma.instanceSetting.upsert({
      where: { key },
      create: { key, value: stored },
      update: { value: stored },
    });
    this.cache.set(key, parsed.data);
    // Values stay out of the trail: legal texts are long, and future keys
    // could be sensitive — the key names what changed, the log has the actor.
    await this.audit.record({
      action: 'settings.changed',
      actorId: actorUserId,
      targetType: 'setting',
      targetId: key,
    });
    return parsed.data as InstanceSettingValue<K>;
  }
}