import type { BackendContext } from '@jaspers-ai/sdk'
import { AGENT_ID, agentIdOf, parseAgent, serializeAgent, type Agent, type AgentInput } from './agents.ts'
import { errorText } from './errors.ts'

// Agents on disk, in the plugin's data folder's defs/, one Markdown file each. The list is the live
// value `agents`, which the view reads, published again whenever the folder changes.

const FOLDER = 'defs'

export async function loadAgents(ctx: BackendContext): Promise<Agent[]> {
  const agents: Agent[] = []
  for (const entry of await ctx.files.list(FOLDER)) {
    const id = entry.dir ? null : agentIdOf(entry.path)
    if (id === null) continue
    try {
      agents.push(parseAgent(id, await ctx.files.read(entry.path)))
    } catch (err) {
      // Gone between the listing and the read, or unreadable: listed with why, not a broken list.
      agents.push({ ...parseAgent(id, ''), error: `could not be read: ${errorText(err, 'unreadable')}` })
    }
  }
  return agents.sort((a, b) => a.name.localeCompare(b.name) || a.id.localeCompare(b.id))
}

export async function publishAgents(ctx: BackendContext): Promise<Agent[]> {
  const agents = await loadAgents(ctx)
  ctx.live.set('agents', agents)
  return agents
}

/** Writes one agent, refusing what would not read back as a working one. */
export async function saveAgent(ctx: BackendContext, input: AgentInput): Promise<void> {
  const text = serializeAgent(input)
  const checked = parseAgent(input.id, text)
  if (checked.error) throw new Error(`Not saved: ${checked.error}.`)
  await ctx.files.write(`${FOLDER}/${input.id}.md`, text)
}

export async function deleteAgent(ctx: BackendContext, id: string): Promise<void> {
  if (!AGENT_ID.test(id)) throw new Error(`No agent ${id}.`)
  await ctx.files.remove(`${FOLDER}/${id}.md`)
}

export function watchAgents(ctx: BackendContext): void {
  ctx.files.watch(FOLDER, () => {
    publishAgents(ctx).catch((err: unknown) => console.warn(`agents: ${errorText(err, 'failed')}`))
  })
}