local acquisition_service_factory = require("clever_f.acquisition_service")
local domain = require("clever_f.domain")
local feedback_service_factory = require("clever_f.feedback_service")
local policy = require("clever_f.policy")
local repeat_resolver_factory = require("clever_f.repeat_resolver")
local sequence_state = require("clever_f.sequence_state")
local state_transitions = require("clever_f.state_transitions")

local M = {}
local SequenceCoordinator = {}
SequenceCoordinator.__index = SequenceCoordinator
M.SequenceCoordinator = SequenceCoordinator

local coordinator_records = setmetatable({}, { __mode = "k" })

local function fail(message, level)
  error(message, (level or 1) + 1)
end

local function descriptor_text(value)
  if domain.Descriptor.is(value) then
    return value.value
  end
  return tostring(value)
end

function M.validate_primary_descriptor(value)
  local descriptor = domain.Descriptor.try_from_string(value)
  if descriptor == nil then
    fail("clever-f: Invalid mapping '" .. descriptor_text(value) .. "'", 2)
  end
  return descriptor
end

function SequenceCoordinator.new(options)
  if SequenceCoordinator.is(options) then
    return options
  end
  if type(options) ~= "table" then
    fail("SequenceCoordinator options must be a table", 2)
  end
  local host = options.host or options
  local state = options.state or sequence_state.get()
  if not sequence_state.is(state) then
    fail("SequenceCoordinator state must be the plugin-global SequenceState", 2)
  end
  local transitions = options.transitions
    or options.state_transitions
    or state_transitions.new(state)
  local policy_service = options.policy
    or options.policy_service
    or policy.new(host)
  local resolver = options.repeat_resolver
    or options.resolver
    or repeat_resolver_factory.new({
      state = state,
      transitions = transitions,
      policy = policy_service,
      clock = host,
    })
  if type(resolver) ~= "table" or type(resolver.decide) ~= "function" then
    fail("SequenceCoordinator repeat resolver must provide decide", 2)
  end
  local feedback = options.feedback
    or options.feedback_service
    or feedback_service_factory.new({
      host = host,
      state = state,
      transitions = transitions,
      policy = policy_service,
    })
  local acquisition = options.acquisition
    or options.acquisition_service
    or acquisition_service_factory.new({
      host = host,
      state = state,
      transitions = transitions,
      policy = policy_service,
      feedback = feedback,
    })
  if type(acquisition) ~= "table" or type(acquisition.acquire) ~= "function" then
    fail("SequenceCoordinator acquisition service must provide acquire", 2)
  end

  local coordinator = setmetatable({}, SequenceCoordinator)
  coordinator_records[coordinator] = {
    host = host,
    state = state,
    transitions = transitions,
    policy = policy_service,
    repeat_resolver = resolver,
    feedback = feedback,
    acquisition = acquisition,
  }
  return coordinator
end

function SequenceCoordinator.is(value)
  return type(value) == "table" and coordinator_records[value] ~= nil
end

function SequenceCoordinator:validate_primary_descriptor(value)
  return M.validate_primary_descriptor(value)
end

local function require_primary_reader(host)
  if type(host) ~= "table"
    or type(host.read_mode) ~= "function"
    or type(host.read_cursor) ~= "function"
    or type(host.read_count) ~= "function"
    or type(host.read_macro_state) ~= "function"
  then
    fail("SequenceCoordinator host must provide primary action state", 3)
  end
  return host
end

function SequenceCoordinator:read_primary_invocation()
  local host = require_primary_reader(coordinator_records[self].host)
  local context = domain.ModeContext.from_full_mode(host:read_mode())
  local position = domain.Position.coerce(host:read_cursor())
  local count = domain.Count.new(host:read_count())
  local macro_state = domain.MacroState.new(host:read_macro_state())
  return {
    context = context,
    position = position,
    origin = position,
    count = count,
    macro_state = macro_state,
  }
end

function SequenceCoordinator:inspect_fold_open_policy(invocation)
  if type(invocation) ~= "table" or not domain.Position.is(invocation.position) then
    fail("fold preflight requires primary invocation state", 2)
  end
  local host = coordinator_records[self].host
  if type(host.read_fold_state) ~= "function" then
    fail("SequenceCoordinator host must provide fold state", 2)
  end
  local fold_state = host:read_fold_state()
  if not domain.FoldState.is(fold_state) then
    fail("SequenceCoordinator host must return FoldState", 2)
  end
  return fold_state
end

local function fold_open_enabled(fold_state)
  return fold_state:opens("horizontal") or fold_state:opens("all")
end

function SequenceCoordinator:open_enclosing_folds(invocation, fold_state)
  if type(invocation) ~= "table" or not domain.Position.is(invocation.position) then
    fail("fold opening requires primary invocation state", 2)
  end
  if not domain.FoldState.is(fold_state) then
    fail("fold opening requires FoldState", 2)
  end
  if not fold_open_enabled(fold_state) then
    return 0
  end

  local host = coordinator_records[self].host
  if type(host.open_fold) ~= "function" then
    fail("SequenceCoordinator host must open folds", 2)
  end
  local opened = 0
  while fold_state.closed_levels > 0 do
    if host:open_fold(invocation.position) ~= true then
      break
    end
    opened = opened + 1
    fold_state = self:inspect_fold_open_policy(invocation)
  end
  return opened
end

function SequenceCoordinator:decide_primary(invocation)
  if type(invocation) ~= "table"
    or not domain.ModeContext.is(invocation.context)
    or not domain.Position.is(invocation.position)
    or not domain.MacroState.is(invocation.macro_state)
  then
    fail("primary decision requires invocation state", 2)
  end
  return coordinator_records[self].repeat_resolver:decide(
    invocation.context,
    invocation.position,
    invocation.macro_state
  )
end

function SequenceCoordinator:acquire_primary(descriptor, invocation)
  descriptor = self:validate_primary_descriptor(descriptor)
  if type(invocation) ~= "table" then
    fail("primary acquisition requires invocation state", 2)
  end
  return coordinator_records[self].acquisition:acquire(
    descriptor,
    invocation.context,
    invocation.position,
    invocation.count,
    invocation.macro_state
  )
end

function SequenceCoordinator:resolve_acquisition(descriptor, invocation)
  local result = self:acquire_primary(descriptor, invocation)
  if type(result.has_outcome) ~= "function" then
    fail("AcquisitionService must return an AcquisitionResult", 2)
  end
  if result:has_outcome() then
    return result.outcome
  end
  return result
end

function SequenceCoordinator:primary(value)
  local descriptor = self:validate_primary_descriptor(value)
  local invocation = self:read_primary_invocation()
  invocation.fold_state = self:inspect_fold_open_policy(invocation)
  invocation.opened_folds = self:open_enclosing_folds(
    invocation,
    invocation.fold_state
  )
  invocation.repeat_decision = self:decide_primary(invocation)
  if invocation.repeat_decision == repeat_resolver_factory.Decision.ACQUIRE then
    return self:resolve_acquisition(descriptor, invocation)
  end
  return descriptor
end

function M.new(options)
  return SequenceCoordinator.new(options)
end

setmetatable(M, {
  __call = function(_, options)
    return SequenceCoordinator.new(options)
  end,
})

return M