local status = require 'bugabinga.pivi.status'

local VARIABLE = 'pivi'
local EVENT = 'User'
local STATUS_PATTERN = 'PiviStatus'
local ACTIVITY_PATTERN = 'PiviActivity'

local read = function()
  local value = vim.g[VARIABLE]
  if type( value ) ~= 'table' then return { active = nil, sessions = {}, } end
  value.sessions = value.sessions or {}
  return value
end

local write = function( value ) vim.g[VARIABLE] = value end

local emit = function( pattern, data )
  pcall( vim.api.nvim_exec_autocmds, EVENT, { pattern = pattern, data = data, modeline = false, } )
end

--- Caches one session's semantic status and announces the change.
--- Consumers read the cached variable; they never perform RPC.
local session_status = function( name, state )
  vim.validate( 'name', name, 'string' )
  vim.validate( 'state', state, 'table' )

  local value = read()
  value.sessions[name] = {
    name = name,
    connection = state.connection,
    run = state.run,
    tool = state.tool,
    queue = state.queue,
    compacting = state.compacting,
    retry = state.retry,
    error = state.error,
    model = state.model,
    thinking = state.thinking,
    session = state.session,
    context = state.context,
    summary = status.summary( state ),
  }
  value.active = value.active or name
  write( value )
  emit( STATUS_PATTERN, { session = name, status = value.sessions[name], } )
end

local set_active = function( name )
  local value = read()
  value.active = name
  write( value )
  emit( STATUS_PATTERN, { session = name, status = value.sessions[name], } )
end

local remove = function( name )
  local value = read()
  value.sessions[name] = nil
  if value.active == name then
    value.active = next( value.sessions )
  end
  write( value )
  emit( STATUS_PATTERN, { session = name, status = nil, } )
end

local activity = function( payload )
  emit( ACTIVITY_PATTERN, payload )
end

--- Cached statusline text. Safe when pivi never started.
local summary = function( name )
  local value = read()
  local key = name or value.active
  if not key then return '' end
  local entry = value.sessions[key]
  if not entry then return '' end
  return entry.summary or ''
end

local reset = function()
  write( { active = nil, sessions = {}, } )
end

return {
  variable = VARIABLE,
  status_pattern = STATUS_PATTERN,
  activity_pattern = ACTIVITY_PATTERN,
  read = read,
  session_status = session_status,
  set_active = set_active,
  remove = remove,
  activity = activity,
  summary = summary,
  reset = reset,
}