-- WirePlumber
--
-- Copyright © 2021 Collabora Ltd.
--    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
--
-- Based on default-routes.c from pipewire-media-session
-- Copyright © 2020 Wim Taymans
--
-- SPDX-License-Identifier: MIT

local config = ...

-- whether to store state on the file system
use_persistent_storage = config["use-persistent-storage"] or false

-- table of device info
dev_infos = {}

-- the state storage
state = use_persistent_storage and State("default-routes") or nil
state_table = state and state:load() or {}

-- simple serializer {"foo", "bar"} -> "foo;bar;"
function serializeArray(a)
  local str = ""
  for _, v in ipairs(a) do
    str = str .. tostring(v):gsub(";", "\\;") .. ";"
  end
  return str
end

-- simple deserializer "foo;bar;" -> {"foo", "bar"}
function parseArray(str, convert_value)
  local array = {}
  local val = ""
  local escaped = false
  for i = 1, #str do
    local c = str:sub(i,i)
    if c == '\\' then
      escaped = true
    elseif c == ';' and not escaped then
      val = convert_value and convert_value(val) or val
      table.insert(array, val)
      val = ""
    else
      val = val .. tostring(c)
      escaped = false
    end
  end
  return array
end

function arrayContains(a, value)
  for _, v in ipairs(a) do
    if v == value then
      return true
    end
  end
  return false
end

function parseParam(param, id)
  local route = param:parse()
  if route.pod_type == "Object" and route.object_id == id then
    return route.properties
  else
    return nil
  end
end

function storeAfterTimeout()
  if timeout_source then
    timeout_source:destroy()
  end
  timeout_source = Core.timeout_add(1000, function ()
    local saved, err = state:save(state_table)
    if not saved then
      Log.warning(err)
    end
    timeout_source = nil
  end)
end

function saveProfile(dev_info, profile_name)
  if not use_persistent_storage then
    return
  end

  local routes = {}
  for idx, ri in pairs(dev_info.route_infos) do
    if ri.save then
      table.insert(routes, ri.name)
    end
  end

  if #routes > 0 then
    local key = dev_info.name .. ":profile:" .. profile_name
    state_table[key] = serializeArray(routes)
    storeAfterTimeout()
  end
end

function saveRouteProps(dev_info, route)
  if not use_persistent_storage or not route.props then
    return
  end

  local props = route.props.properties
  local key_base = dev_info.name .. ":" ..
                   route.direction:lower() .. ":" ..
                   route.name .. ":"

  state_table[key_base .. "volume"] =
    props.volume and tostring(props.volume) or nil
  state_table[key_base .. "mute"] =
    props.mute and tostring(props.mute) or nil
  state_table[key_base .. "channelVolumes"] =
    props.channelVolumes and serializeArray(props.channelVolumes) or nil
  state_table[key_base .. "channelMap"] =
    props.channelMap and serializeArray(props.channelMap) or nil
  state_table[key_base .. "latencyOffsetNsec"] =
    props.latencyOffsetNsec and tostring(props.latencyOffsetNsec) or nil
  state_table[key_base .. "iec958Codecs"] =
    props.iec958Codecs and serializeArray(props.iec958Codecs) or nil

  storeAfterTimeout()
end

function restoreRoute(device, dev_info, device_id, route)
  -- default props
  local props = {
    "Spa:Pod:Object:Param:Props", "Route",
    channelVolumes = { 0.4 },
    mute = false,
  }

  -- restore props from persistent storage
  if use_persistent_storage then
    local key_base = dev_info.name .. ":" ..
                     route.direction:lower() .. ":" ..
                     route.name .. ":"

    local str = state_table[key_base .. "volume"]
    props.volume = str and tonumber(str) or props.volume

    local str = state_table[key_base .. "mute"]
    props.mute = str and (str == "true") or false

    local str = state_table[key_base .. "channelVolumes"]
    props.channelVolumes = str and parseArray(str, tonumber) or props.channelVolumes

    local str = state_table[key_base .. "channelMap"]
    props.channelMap = str and parseArray(str) or props.channelMap

    local str = state_table[key_base .. "latencyOffsetNsec"]
    props.latencyOffsetNsec = str and math.tointeger(str) or props.latencyOffsetNsec

    local str = state_table[key_base .. "iec958Codecs"]
    props.iec958Codecs = str and parseArray(str) or props.iec958Codecs
  end

  -- convert arrays to Spa Pod
  if props.channelVolumes then
    table.insert(props.channelVolumes, 1, "Spa:Float")
    props.channelVolumes = Pod.Array(props.channelVolumes)
  end
  if props.channelMap then
    table.insert(props.channelMap, 1, "Spa:Enum:AudioChannel")
    props.channelMap = Pod.Array(props.channelMap)
  end
  if props.iec958Codecs then
    table.insert(props.iec958Codecs, 1, "Spa:Enum:AudioIEC958Codec")
    props.iec958Codecs = Pod.Array(props.iec958Codecs)
  end

  -- construct Route param
  local param = Pod.Object {
    "Spa:Pod:Object:Param:Route", "Route",
    index = route.index,
    device = device_id,
    props = Pod.Object(props),
    save = route.save,
  }

  Log.debug(param, "setting route on " .. tostring(device))
  device:set_param("Route", param)

  route.prev_active = true
  route.active = true
end

function findActiveDeviceIDs(profile)
  -- parses the classes from the profile and returns the device IDs
  ----- sample structure, should return { 0, 8 } -----
  -- classes:
  --  1: 2
  --  2:
  --    1: Audio/Source
  --    2: 1
  --    3: card.profile.devices
  --    4:
  --      1: 0
  --      pod_type: Array
  --      value_type: Spa:Int
  --    pod_type: Struct
  --  3:
  --    1: Audio/Sink
  --    2: 1
  --    3: card.profile.devices
  --    4:
  --      1: 8
  --      pod_type: Array
  --      value_type: Spa:Int
  --    pod_type: Struct
  --  pod_type: Struct
  local active_ids = {}
  if type(profile.classes) == "table" and profile.classes.pod_type == "Struct" then
    for _, p in ipairs(profile.classes) do
      if type(p) == "table" and p.pod_type == "Struct" then
        local i = 1
        while true do
          local k, v = p[i], p[i+1]
          i = i + 2
          if not k or not v then
            break
          end
          if k == "card.profile.devices" and
              type(v) == "table" and v.pod_type == "Array" then
            for _, dev_id in ipairs(v) do
              table.insert(active_ids, dev_id)
            end
          end
        end
      end
    end
  end
  return active_ids
end

-- returns an array of the route names that were previously selected
-- for the given device and profile
function getStoredProfileRoutes(dev_name, profile_name)
  local key = dev_name .. ":profile:" .. profile_name
  local str = state_table[key]
  return str and parseArray(str) or {}
end

-- find a route that was previously stored for a device_id
-- spr needs to be the array returned from getStoredProfileRoutes()
function findSavedRoute(dev_info, device_id, spr)
  for idx, ri in pairs(dev_info.route_infos) do
    if arrayContains(ri.devices, device_id) and arrayContains(spr, ri.name) then
      return ri
    end
  end
  return nil
end

-- find the best route for a given device_id, based on availability and priority
function findBestRoute(dev_info, device_id)
  local best_avail = nil
  local best_unk = nil
  for idx, ri in pairs(dev_info.route_infos) do
    if arrayContains(ri.devices, device_id) then
      if ri.available == "yes" or ri.available == "unknown" then
        if ri.direction == "Output" and ri.available ~= ri.prev_available then
          best_avail = ri
          ri.save = true
          break
        elseif ri.available == "yes" then
          if (best_avail == nil or ri.priority > best_avail.priority) then
            best_avail = ri
          end
        elseif best_unk == nil or ri.priority > best_unk.priority then
            best_unk = ri
        end
      end
    end
  end
  return best_avail or best_unk
end

function restoreProfileRoutes(device, dev_info, profile, profile_changed)
  Log.info(device, "restore routes for profile " .. profile.name)

  local active_ids = findActiveDeviceIDs(profile)
  local spr = getStoredProfileRoutes(dev_info.name, profile.name)

  for _, device_id in ipairs(active_ids) do
    Log.info(device, "restoring device " .. device_id);

    local route = nil

    -- restore routes selection for the newly selected profile
    -- don't bother if spr is empty, there is no point
    if profile_changed and #spr > 0 then
      route = findSavedRoute(dev_info, device_id, spr)
      if route then
        -- we found a saved route
        if route.available == "no" then
          Log.info(device, "saved route '" .. route.name .. "' not available")
          -- not available, try to find next best
          route = nil
        else
          Log.info(device, "found saved route: " .. route.name)
          -- make sure we save it again
          route.save = true
        end
      end
    end

    -- we could not find a saved route, try to find a new best
    if not route then
      route = findBestRoute(dev_info, device_id)
      if not route then
        Log.info(device, "can't find best route")
      else
        Log.info(device, "found best route: " .. route.name)
      end
    end

    -- restore route
    if route then
      restoreRoute(device, dev_info, device_id, route)
    end
  end
end

function findRouteInfo(dev_info, route, return_new)
  local ri = dev_info.route_infos[route.index]
  if not ri and return_new then
    ri = {
      index = route.index,
      name = route.name,
      direction = route.direction,
      devices = route.devices or {},
      priority = route.priority or 0,
      available = route.available or "unknown",
      prev_available = route.available or "unknown",
      active = false,
      prev_active = false,
      save = false,
    }
  end
  return ri
end

function handleDevice(device)
  local dev_info = dev_infos[device["bound-id"]]
  local new_route_infos = {}
  local avail_routes_changed = false

  -- look at all the routes and update/reset cached information
  for p in device:iterate_params("EnumRoute") do
    -- parse pod
    local route = parseParam(p, "EnumRoute")
    if not route then
      goto skip_enum_route
    end

    -- find cached route information
    local route_info = findRouteInfo(dev_info, route, true)

    -- update properties
    route_info.prev_available = route_info.available
    if route_info.available ~= route.available then
      Log.info(device, "route " .. route.name .. " available changed " ..
                       route_info.available .. " -> " .. route.available)
      route_info.available = route.available
      avail_routes_changed = true
    end
    route_info.prev_active = route_info.active
    route_info.active = false
    route_info.save = false

    -- store
    new_route_infos[route.index] = route_info

    ::skip_enum_route::
  end

  -- replace old route_infos to lose old routes
  -- that no longer exist on the device
  dev_info.route_infos = new_route_infos
  new_route_infos = nil

  -- check for changes in the active routes
  for p in device:iterate_params("Route") do
    local route = parseParam(p, "Route")
    if not route then
      goto skip_route
    end

    -- get cached route info and at the same time
    -- ensure that the route is also in EnumRoute
    local route_info = findRouteInfo(dev_info, route, false)
    if not route_info then
      goto skip_route
    end

    -- update state
    route_info.active = true
    route_info.save = route.save

    if not route_info.prev_active then
      -- a new route is now active, restore the volume and
      -- make sure we save this as a preferred route
      Log.info(device, "new active route found " .. route.name)
      restoreRoute(device, dev_info, route.device, route_info)
    elseif route.save then
      -- just save route properties
      Log.info(device, "storing route props for " .. route.name)
      saveRouteProps(dev_info, route)
    end

    ::skip_route::
  end

  -- now get the profile and restore routes for it
  for p in device:iterate_params("Profile") do
    local profile = parseParam(p, "Profile")
    if profile then
      local profile_changed = (dev_info.active_profile ~= profile.index)

      -- if the profile changed, restore routes for that profile
      -- if any of the routes of the current profile changed in availability,
      -- then try to select a new "best" route for each device and ignore
      -- what was stored
      if profile_changed or avail_routes_changed then
        dev_info.active_profile = profile.index
        restoreProfileRoutes(device, dev_info, profile, profile_changed)
      end

      saveProfile(dev_info, profile.name)
    end
  end
end

om = ObjectManager {
  Interest {
    type = "device",
    Constraint { "device.name", "is-present", type = "pw-global" },
  }
}

om:connect("objects-changed", function (om)
  local new_dev_infos = {}
  for device in om:iterate() do
    local dev_info = dev_infos[device["bound-id"]]
    -- new device appeared
    if not dev_info then
      dev_info = {
        name = device.properties["device.name"],
        active_profile = -1,
        route_infos = {},
      }
      dev_infos[device["bound-id"]] = dev_info

      device:connect("params-changed", handleDevice)
      handleDevice(device)
    end

    new_dev_infos[device["bound-id"]] = dev_info
  end
  -- replace list to get rid of dev_info for devices that no longer exist
  dev_infos = new_dev_infos
end)

om:activate()
