import {
  AdminAuditQuery,
  AdminErrorListQuery,
  ResolveErrorInput,
  RoleChangeInput,
} from '@impuestos/contracts';
import { Hono } from 'hono';
import type { z } from 'zod';
import { ADMIN_ROLES } from '../../auth/options';
import {
  auditRowsForExport,
  changeRole,
  listAdminErrors,
  listAudit,
  resolveIngestError,
  retryJob,
  searchUsers,
  toCsv,
  userOverview,
} from '../../modules/admin';
import { type AuditAction, writeAudit } from '../../modules/audit';
import type { AppDeps, AppEnv, SessionUser } from '../context';
import { HttpError } from '../errors';
import { requireRole } from '../middleware';

const SUPERADMIN_ONLY = ['superadmin'] as const;

/**
 * FLOWS.md Flow H. Two rules hold for every handler here: the role is checked in the
 * handler and not only at the router, and anything that reads or changes a user's data
 * writes an audit row before it answers.
 */
export function adminRoutes(deps: AppDeps): Hono<AppEnv> {
  const routes = new Hono<AppEnv>();
  const db = deps.handle.db;

  routes.get('/users/search', async (c) => {
    const staff = requireRole(c, ADMIN_ROLES);
    const term = c.req.query('q') ?? '';
    const items = await searchUsers(db, term);

    await audit(c, deps, staff, {
      action: 'admin.user_search',
      subjectUserId: null,
      resource: 'user',
      detail: { q: term, results: items.length },
    });

    return c.json({ items });
  });

  routes.get('/users/:id/overview', async (c) => {
    const staff = requireRole(c, ADMIN_ROLES);
    const id = c.req.param('id');
    const overview = await userOverview(db, id);
    if (!overview) throw new HttpError('not_found');

    // CONTRACTS.md section 5.5 pins this: one view, exactly one `admin.user_lookup` row.
    await audit(c, deps, staff, {
      action: 'admin.user_lookup',
      subjectUserId: id,
      resource: `user/${id}`,
    });

    return c.json(overview);
  });

  routes.post('/users/:id/role', async (c) => {
    const actor = requireRole(c, SUPERADMIN_ONLY);
    const id = c.req.param('id');
    const input = parse(RoleChangeInput, await body(c));

    const result = await changeRole(db, {
      actorUserId: actor.id,
      targetUserId: id,
      role: input.role,
    });
    if (!result.ok) {
      if (result.reason === 'not_found') throw new HttpError('not_found');
      throw new HttpError('conflict', { field: 'role', detail: { reason: result.reason } });
    }

    await audit(c, deps, actor, {
      action: 'admin.role_change',
      subjectUserId: id,
      resource: `user/${id}`,
      detail: { from: result.previous, to: input.role },
    });

    return c.json({ ok: true } as const);
  });

  routes.get('/errors', async (c) => {
    requireRole(c, ADMIN_ROLES);
    const query = parse(AdminErrorListQuery, {
      stage: c.req.query('stage'),
      status: c.req.query('status'),
      cursor: c.req.query('cursor'),
    });
    return c.json(await listAdminErrors(db, query));
  });

  routes.post('/errors/:id/resolve', async (c) => {
    const staff = requireRole(c, ADMIN_ROLES);
    const id = c.req.param('id');
    const input = parse(ResolveErrorInput, await body(c));

    const result = await resolveIngestError(db, id, { userId: staff.id, note: input.note });
    if (!result.ok) {
      if (result.reason === 'not_found') throw new HttpError('not_found');
      throw new HttpError('conflict', { detail: { reason: result.reason } });
    }

    await audit(c, deps, staff, {
      action: 'admin.error_resolve',
      subjectUserId: null,
      resource: `ingest_errors/${id}`,
      detail: { note: input.note },
    });

    return c.json({ ok: true } as const);
  });

  routes.post('/jobs/:id/retry', async (c) => {
    const staff = requireRole(c, ADMIN_ROLES);
    const id = c.req.param('id');

    const result = await retryJob(db, id);
    if (!result.ok) {
      if (result.reason === 'not_found') throw new HttpError('not_found');
      throw new HttpError('conflict', { detail: { reason: result.reason } });
    }

    await audit(c, deps, staff, {
      action: 'admin.job_retry',
      subjectUserId: null,
      resource: `jobs/${id}`,
    });

    return c.json({ ok: true } as const);
  });

  /**
   * Reading the log is not itself audited. A row for every scroll of the audit screen
   * would bury the accesses that matter under the act of looking for them. Taking a copy
   * out of the building is a different thing, so the CSV export below is audited.
   */
  routes.get('/audit', async (c) => {
    requireRole(c, ADMIN_ROLES);
    return c.json(await listAudit(db, auditQuery(c)));
  });

  routes.get('/audit/export.csv', async (c) => {
    const staff = requireRole(c, ADMIN_ROLES);
    const query = auditQuery(c);
    const rows = await auditRowsForExport(db, query);

    await audit(c, deps, staff, {
      action: 'admin.audit_export',
      subjectUserId: null,
      resource: 'audit_log',
      detail: { rows: rows.length, ...query },
    });

    return new Response(toCsv(rows), {
      headers: {
        'content-type': 'text/csv; charset=utf-8',
        'content-disposition': `attachment; filename="audit-${new Date().toISOString().slice(0, 10)}.csv"`,
      },
    });
  });

  return routes;
}

function auditQuery(c: { req: { query: (name: string) => string | undefined } }): AdminAuditQuery {
  return parse(AdminAuditQuery, {
    actor: c.req.query('actor'),
    action: c.req.query('action'),
    subject: c.req.query('subject'),
    from: c.req.query('from'),
    to: c.req.query('to'),
    cursor: c.req.query('cursor'),
  });
}

async function body(c: { req: { json: () => Promise<unknown> } }): Promise<unknown> {
  try {
    return await c.req.json();
  } catch {
    throw new HttpError('validation_error');
  }
}

function parse<T>(schema: z.ZodType<T>, value: unknown): T {
  const result = schema.safeParse(value);
  if (!result.success) {
    const issue = result.error.issues[0];
    throw new HttpError('validation_error', {
      ...(issue?.path.length ? { field: issue.path.join('.') } : {}),
      detail: result.error.issues,
    });
  }
  return result.data;
}

function audit(
  c: { req: { header: (name: string) => string | undefined } },
  deps: AppDeps,
  actor: SessionUser,
  entry: {
    action: AuditAction;
    subjectUserId: string | null;
    resource: string;
    detail?: Record<string, unknown>;
  },
): Promise<void> {
  return writeAudit(deps.handle.db, {
    actorUserId: actor.id,
    actorRole: actor.role,
    ip: c.req.header('x-forwarded-for')?.split(',')[0]?.trim() ?? null,
    ...entry,
  });
}