// What the notes module does, as pure TypeScript over the ports in ports.ts. Every write is one
// transaction with the event that announces it, so the audit event and the usage fact of a change
// exist exactly when the change does (core/subscribers.ts reads the events).
//
// The two things this module does not own are the file and the permission to see it: an attachment
// is a row of the files module, reached through `getFile`, which answers NotFound for another
// tenant's file and for one that does not exist alike (spec §3.3).

import { conflict, forbidden, notFound, validationFailed } from "@conusai-kit/core"
import { type FileView, getFile } from "@conusai-kit/files"
import type { z } from "zod"
import {
  ATTACHMENT_CONTENT_TYPES,
  type AttachmentView,
  attachmentAdded,
  attachmentRemoved,
  attachments,
  MAX_ATTACHMENTS,
  type NoteView,
  noteCreated,
  noteDeleted,
  notes,
  noteUpdated,
} from "../contract/index.js"
import { attachmentsEnabled, type NoteScope, type NotesDeps } from "./ports.js"

type NoteRow = z.output<typeof notes.schema>

const PAGE = 200

class AttachmentConcurrencyConflict extends Error {
  constructor(readonly original: unknown) {
    super("the note changed while another attachment was being added")
  }
}

const ids = (scope: NoteScope) => ({
  orgId: scope.orgId,
  workspaceId: scope.workspaceId,
  projectId: scope.projectId,
})

const noteView = (row: NoteRow, attachmentCount: number): NoteView => ({
  noteId: row.id,
  title: row.title,
  body: row.body,
  version: row.version,
  createdBy: row.createdBy,
  createdAt: row.createdAt,
  updatedAt: row.updatedAt,
  attachmentCount,
})

function attachmentView(
  row: { id: string; fileId: string; createdAt: string },
  file: Pick<FileView, "filename" | "contentType" | "size">,
): AttachmentView {
  return {
    attachmentId: row.id,
    fileId: row.fileId,
    filename: file.filename,
    contentType: file.contentType,
    size: file.size,
    attachedAt: row.createdAt,
  }
}

export async function listNotes(
  deps: NotesDeps,
  scope: NoteScope,
  options: { cursor?: string; limit?: number },
): Promise<{ notes: NoteView[]; cursor?: string; hasMore: boolean }> {
  const repos = deps.data.forScope(scope)
  const page = await repos.of(notes).list({
    order: [{ field: "createdAt", direction: "desc" }],
    ...(options.limit === undefined ? {} : { limit: options.limit }),
    ...(options.cursor === undefined ? {} : { cursor: options.cursor }),
  })
  // The attachment counts of the page's notes in one read over the note index, not one count per
  // note (up to 200 queries for one list).
  const counts = new Map<string, number>()
  if (page.items.length > 0) {
    let linksCursor: string | undefined
    do {
      const attachmentsPage = await repos.of(attachments).list({
        where: [{ field: "noteId", op: "in", values: page.items.map((row) => row.id) }],
        limit: PAGE,
        ...(linksCursor === undefined ? {} : { cursor: linksCursor }),
      })
      for (const link of attachmentsPage.items) counts.set(link.noteId, (counts.get(link.noteId) ?? 0) + 1)
      linksCursor = attachmentsPage.hasMore ? attachmentsPage.cursor : undefined
    } while (linksCursor !== undefined)
  }
  return {
    notes: page.items.map((row) => noteView(row, counts.get(row.id) ?? 0)),
    ...(page.cursor === undefined ? {} : { cursor: page.cursor }),
    hasMore: page.hasMore,
  }
}

async function attachmentRows(deps: NotesDeps, scope: NoteScope, noteId: string) {
  const found = []
  let cursor: string | undefined
  do {
    const page = await deps.data
      .forScope(scope)
      .of(attachments)
      .list({
        where: [{ field: "noteId", op: "eq", value: noteId }],
        order: [{ field: "createdAt", direction: "asc" }],
        limit: PAGE,
        ...(cursor === undefined ? {} : { cursor }),
      })
    found.push(...page.items)
    cursor = page.hasMore ? page.cursor : undefined
  } while (cursor !== undefined)
  return found
}

export async function getNote(
  deps: NotesDeps,
  scope: NoteScope,
  noteId: string,
): Promise<{ note: NoteView; attachments: AttachmentView[]; attachmentsEnabled: boolean }> {
  // NotFound for another tenant's note and for one nobody wrote: the repository answers both the same.
  const row = await deps.data.forScope(scope).of(notes).get(noteId)
  if (!row) throw notFound("no such note")
  const [links, enabled] = await Promise.all([attachmentRows(deps, scope, row.id), attachmentsEnabled(deps, scope)])
  // The files are read together, not one after another: a note carries at most MAX_ATTACHMENTS, and
  // a deleted one (before the relay removed its links) is not a reason to fail the page.
  const files = await Promise.all(
    links.map((link) =>
      getFile(deps.files, scope, link.fileId).catch((error: unknown) => {
        if ((error as { status?: number }).status === 404) return undefined
        throw error
      }),
    ),
  )
  const views: AttachmentView[] = []
  for (const [at, link] of links.entries()) {
    const file = files[at]
    if (file) views.push(attachmentView(link, file))
  }
  return {
    note: noteView(row, views.length),
    attachments: views,
    attachmentsEnabled: enabled,
  }
}

export async function createNote(
  deps: NotesDeps,
  scope: NoteScope,
  input: { title: string; body: string },
): Promise<NoteView> {
  return deps.data.unitOfWork.run(scope, async (tx) => {
    const row = await tx.of(notes).insert({ title: input.title, body: input.body, createdBy: scope.actor.userId })
    await tx.publish(noteCreated, { ...ids(scope), noteId: row.id, createdBy: scope.actor.userId })
    return noteView(row, 0)
  })
}

export async function updateNote(
  deps: NotesDeps,
  scope: NoteScope,
  input: { noteId: string; title: string; body: string; expectedVersion: number },
): Promise<NoteView> {
  return deps.data.unitOfWork.run(scope, async (tx) => {
    const current = await tx.of(notes).get(input.noteId)
    if (!current) throw notFound("no such note")
    // The repository answers 409 when the version is not the row's: two editors never overwrite each other silently.
    const row = await tx.of(notes).update(current.id, { title: input.title, body: input.body }, input.expectedVersion)
    await tx.publish(noteUpdated, {
      ...ids(scope),
      noteId: row.id,
      version: row.version,
      updatedBy: scope.actor.userId,
    })
    const count = await tx.of(attachments).count({ where: [{ field: "noteId", op: "eq", value: row.id }] })
    return noteView(row, count)
  })
}

/**
 * Deletes the note and its links. The files stay: they are the project's, they may be attached to
 * another note, and removing one is `files.file.delete`'s decision, with its own permission.
 */
export async function deleteNote(deps: NotesDeps, scope: NoteScope, noteId: string): Promise<void> {
  await deps.data.unitOfWork.run(scope, async (tx) => {
    const row = await tx.of(notes).get(noteId)
    if (!row) throw notFound("no such note")
    let removed = 0
    for (;;) {
      const page = await tx.of(attachments).list({ where: [{ field: "noteId", op: "eq", value: row.id }], limit: PAGE })
      for (const link of page.items) {
        await tx.of(attachments).delete(link.id)
        removed += 1
      }
      if (!page.hasMore) break
    }
    await tx.of(notes).delete(row.id)
    await tx.publish(noteDeleted, {
      ...ids(scope),
      noteId: row.id,
      deletedBy: scope.actor.userId,
      attachmentCount: removed,
    })
  })
}

/**
 * Links an uploaded file to a note. Idempotent: attaching a file twice answers with the first link
 * and publishes nothing, so a retried request audits once.
 */
export async function addAttachment(
  deps: NotesDeps,
  scope: NoteScope,
  input: { noteId: string; fileId: string },
): Promise<AttachmentView> {
  if (!(await attachmentsEnabled(deps, scope))) throw forbidden("attachments are switched off")
  const file = await getFile(deps.files, scope, input.fileId)
  // The files module accepts more than a note should carry (spreadsheets, say); this module's list is its own.
  if (!(ATTACHMENT_CONTENT_TYPES as readonly string[]).includes(file.contentType)) {
    throw validationFailed([{ path: "fileId", message: `${file.contentType} cannot be attached to a note` }])
  }
  // The count and insert are one transaction, but that alone does not serialize two transactions
  // that attach different files to the same note. Optimistically update the note first: its
  // expected-version write is the portable per-note lock across SQL, MongoDB and Convex. A loser
  // retries the transaction and rechecks both idempotency and the quota against the winner's row.
  for (let attempt = 0; ; attempt += 1) {
    try {
      return await deps.data.unitOfWork.run(scope, async (tx) => {
        const noteRepo = tx.of(notes)
        const note = await noteRepo.get(input.noteId)
        if (!note) throw notFound("no such note")
        const links = tx.of(attachments)
        const existing = (
          await links.list({
            where: [
              { field: "noteId", op: "eq", value: note.id },
              { field: "fileId", op: "eq", value: file.fileId },
            ],
            limit: 1,
          })
        ).items[0]
        if (existing) return attachmentView(existing, file)

        try {
          await noteRepo.update(note.id, {}, note.version)
        } catch (error) {
          if ((error as { status?: number }).status === 409) throw new AttachmentConcurrencyConflict(error)
          throw error
        }
        if ((await links.count({ where: [{ field: "noteId", op: "eq", value: note.id }] })) >= MAX_ATTACHMENTS) {
          throw conflict(`a note carries at most ${MAX_ATTACHMENTS} attachments`)
        }
        const link = await links.insert({ noteId: note.id, fileId: file.fileId, attachedBy: scope.actor.userId })
        await tx.publish(attachmentAdded, {
          ...ids(scope),
          noteId: note.id,
          attachmentId: link.id,
          fileId: file.fileId,
          attachedBy: scope.actor.userId,
        })
        return attachmentView(link, file)
      })
    } catch (error) {
      // A retry that loses the optimistic lock re-reads the winner's link or sees the full quota.
      // Bound retries so sustained contention returns the repository's ordinary conflict response.
      if (!(error instanceof AttachmentConcurrencyConflict)) throw error
      if (attempt >= 7) throw error.original
    }
  }
}

export async function removeAttachment(
  deps: NotesDeps,
  scope: NoteScope,
  input: { noteId: string; attachmentId: string },
): Promise<void> {
  await deps.data.unitOfWork.run(scope, async (tx) => {
    const link = await tx.of(attachments).get(input.attachmentId)
    // The note id is part of the lookup, so a link of another note of this project is not found either.
    if (!link || link.noteId !== input.noteId) throw notFound("no such attachment")
    await tx.of(attachments).delete(link.id)
    await tx.publish(attachmentRemoved, {
      ...ids(scope),
      noteId: link.noteId,
      attachmentId: link.id,
      fileId: link.fileId,
      removedBy: scope.actor.userId,
    })
  })
}