import { derived, type Readable } from 'svelte/store'
import { messages, chatFor, type ChatMessage, type ToolCallResult } from './chat'
import { planSteps, currentTask, workspaceFor, taskFor } from './workspace'
import { liveExecutionOutputFor, type LiveExecutionOutput } from './execstream'
import type { PlanStep, Session } from '$lib/api'

export { type ToolCallResult }

export interface ActivityEntry {
  id: string
  type:
    | 'goal'
    | 'plan'
    | 'step_running'
    | 'step_done'
    | 'step_failed'
    | 'tool_running'
    | 'tool_done'
    | 'tool_error'
    | 'knowledge'
    | 'complete'
    | 'question'
    | 'error'
  description: string
  detail?: string
  args?: string
  timestamp: number
  toolName?: string
  stepSeq?: number
  indent?: boolean
  status: 'running' | 'done' | 'failed'
  // Command output streaming in while a `run` tool call is still executing.
  // Distinct from `detail`, which is only populated once the tool_result
  // arrives — for an auto-run that is the moment the command finishes.
  liveOutput?: string
}

// Detail text is kept full-length (not hard-truncated to a preview snippet)
// so the expanded view has something worth pretty-printing — capped only as
// a safety net against pathological payloads (a full fleet dump, etc).
const DETAIL_MAX = 8000

function summarizeArgs(args: unknown): string | undefined {
  if (!args || typeof args !== 'object' || Array.isArray(args)) return undefined
  if (Object.keys(args).length === 0) return undefined
  try {
    return JSON.stringify(args)
  } catch {
    return undefined
  }
}

function stringifyResult(result: unknown): string {
  const s = typeof result === 'string' ? result : JSON.stringify(result ?? '')
  return s.length > DETAIL_MAX ? `${s.slice(0, DETAIL_MAX)}\n… truncated` : s
}

// Pure derivation, parameterized so it can back both the global "current
// session" activityLog below and a per-session activityLogFor(sessionId) for
// a floating task window.
function computeActivityLog(
  $msgs: ChatMessage[],
  $steps: PlanStep[],
  $task: Session | null
): ActivityEntry[] {
  const entries: ActivityEntry[] = []
  const now = Date.now()

  // Goal
  if ($task?.goal) {
    entries.push({
      id: 'goal',
      type: 'goal',
      description: $task.goal,
      timestamp: 0,
      status: 'done'
    })
  }

  // Plan steps
  for (const s of $steps) {
    if (s.status === 'pending') continue
    const stepLabel = s.title || `Step ${s.seq}`
    entries.push({
      id: s.id,
      type:
        s.status === 'running' ? 'step_running' : s.status === 'done' ? 'step_done' : 'step_failed',
      description: `Step ${s.seq}: ${stepLabel}`,
      detail: s.detail || undefined,
      timestamp: s.started_at ? new Date(s.started_at).getTime() : now,
      status: s.status === 'running' ? 'running' : s.status === 'done' ? 'done' : 'failed'
    })
  }

  // Tool calls (from messages). Tag each tool with the plan step that's
  // currently running when it fires.
  let currentStepSeq = 0
  let entryIdx = 0
  for (let mi = 0; mi < $msgs.length; mi++) {
    for (const t of $msgs[mi].tools) {
      // Track current step from update_plan_step calls
      if (t.type === 'tool_use' && t.name === 'update_plan_step') {
        const s = typeof t.args?.seq === 'number' ? t.args.seq : undefined
        const status = typeof t.args?.status === 'string' ? t.args.status : undefined
        if (s && status === 'running') currentStepSeq = s
      } else if (t.name === 'set_goal' || t.name === 'propose_plan' || t.name === 'complete_task') {
        currentStepSeq = 0
      }

      const label = toolActivityLabel(t)
      const stepTag = currentStepSeq > 0 ? currentStepSeq : undefined
      if (t.type === 'tool_use') {
        entries.push({
          id: t.id ?? `tool_${mi}_${entryIdx++}`,
          type: 'tool_running',
          description: label,
          args: summarizeArgs(t.args),
          timestamp: now - ($msgs.length - mi) * 1000,
          toolName: t.name,
          stepSeq: stepTag,
          indent: stepTag != null,
          status: 'running'
        })
      } else if (t.type === 'tool_result') {
        const running = entries.find(
          (e) => e.type === 'tool_running' && e.id === t.id && e.status === 'running'
        )
        if (running && t.error) {
          running.type = 'tool_error'
          running.status = 'failed'
          running.description = `${label}: ${t.error.slice(0, 80)}`
          running.detail = t.error
        } else if (running) {
          running.type = 'tool_done'
          running.status = 'done'
          running.detail = stringifyResult(t.result)
        } else {
          // Historical/persisted tool calls arrive as one merged record (args
          // + result on the same object, see mergeToolCalls in chat.ts) rather
          // than a separate tool_use/tool_result pair — there's never a
          // "running" entry to attach to, so this branch has to build the
          // full entry itself. It used to fall back to the raw tool name
          // (e.g. "get_entity") instead of the humanized label here.
          entries.push({
            id: t.id ?? `tool_${mi}_${entryIdx++}`,
            type: t.error ? 'tool_error' : 'tool_done',
            description: t.error ? `${label}: ${t.error.slice(0, 80)}` : label,
            detail: t.error ? t.error : stringifyResult(t.result),
            args: summarizeArgs(t.args),
            timestamp: now - ($msgs.length - mi) * 1000,
            toolName: t.name,
            stepSeq: stepTag,
            indent: stepTag != null,
            status: t.error ? 'failed' : 'done'
          })
        }
      }
    }
  }

  // Knowledge recorded — detect from upsert_knowledge tool results
  for (let mi = 0; mi < $msgs.length; mi++) {
    for (const t of $msgs[mi].tools) {
      if (t.type === 'tool_result' && t.name === 'upsert_knowledge' && !t.error) {
        const title = typeof t.args?.title === 'string' ? t.args.title : ''
        entries.push({
          id: `knowledge_${mi}`,
          type: 'knowledge',
          description: title ? `Recorded: ${title.slice(0, 60)}` : 'Recorded knowledge',
          timestamp: now - ($msgs.length - mi) * 1000,
          status: 'done'
        })
      }
    }
  }

  // Task completion
  if ($task?.outcome) {
    entries.push({
      id: 'complete',
      type: 'complete',
      description: $task.summary || `Task ${$task.outcome}`,
      timestamp: now,
      status: $task.outcome === 'failure' ? 'failed' : 'done'
    })
  }

  // Note: approval entries were removed from activityLog (2026-07-15).
  // They were always `status: 'running'` and never transitioned to 'done'
  // (the derived store builds from tool-call text, not execution status),
  // which caused the AgentIndicator to latch onto a stale "Approval: ..."
  // entry and never clear — even after the session completed. Approvals
  // are tracked via the REST /approvals endpoint (context.ts, Ops.svelte)
  // and rendered as inline approval cards in the chat (or Ops page), not
  // in the activity log.

  // Sort oldest first
  entries.sort((a, b) => a.timestamp - b.timestamp)

  return entries
}

export const activityLog = derived([messages, planSteps, currentTask], ([$msgs, $steps, $task]) =>
  computeActivityLog($msgs, $steps, $task)
)

// Attach streaming output to the `run` entry that is currently executing.
// Nomos runs tools sequentially, so the last still-running run entry is the
// one the output belongs to.
function withLiveOutput(
  entries: ActivityEntry[],
  live: LiveExecutionOutput | null
): ActivityEntry[] {
  if (!live?.output) return entries
  for (let i = entries.length - 1; i >= 0; i--) {
    const e = entries[i]
    if (e.type === 'tool_running' && e.status === 'running' && e.toolName === 'run') {
      entries[i] = { ...e, liveOutput: live.output }
      break
    }
  }
  return entries
}

export function activityLogFor(sessionId: string): Readable<ActivityEntry[]> {
  const chat = chatFor(sessionId)
  const ws = workspaceFor(sessionId)
  const task = taskFor(sessionId)
  const live = liveExecutionOutputFor(sessionId)
  return derived([chat.messages, ws.planSteps, task, live], ([$msgs, $steps, $task, $live]) =>
    withLiveOutput(computeActivityLog($msgs, $steps, $task), $live)
  )
}

// Humanized, past/present-tense description of what a tool call is doing
// ("Check execution", "Research: …") rather than its raw wire name. Exported
// so the chat's agent trace can read as a thinking log instead of an API log.
export function toolActivityLabel(t: ToolCallResult): string {
  const args = t.args ?? {}
  const str = (v: unknown): string => (typeof v === 'string' ? v : '')
  switch (t.name) {
    case 'set_goal':
      return 'Set goal'
    case 'propose_plan':
      return 'Proposed plan'
    case 'search_knowledge':
      return `Research: ${str(args.query)}`
    case 'get_entity':
      return `Lookup: ${str(args.slug_or_id)}`
    case 'get_entity_knowledge':
      return 'Check prior knowledge'
    case 'get_relations':
      return 'Check relationships'
    case 'list_lxcs':
      return 'List containers'
    case 'list_entities':
      return 'List entities'
    case 'get_health_summary':
      return 'Fleet health'
    case 'get_state_snapshot':
      return 'State snapshot'
    case 'run': {
      const purpose = str(args.purpose)
      const target = str(args.target)
      if (purpose) return purpose
      if (target) return `Run on ${target}`
      return 'Run command'
    }
    case 'get_execution_status':
      return 'Check execution'
    case 'update_plan_step':
      return 'Update plan'
    case 'upsert_knowledge':
      return 'Record knowledge'
    case 'complete_task':
      return 'Complete task'
    case 'ping_service':
      return 'Check service'
    case 'ask_operator':
      return 'Ask operator'
    // Unmapped tool (new/uncommon) — humanize the raw name rather than
    // showing it verbatim, e.g. "revoke_execution" -> "Revoke execution".
    default:
      return t.name.replace(/_/g, ' ').replace(/^./, (c) => c.toUpperCase())
  }
}