--[[
  ReAction bar state driver interface

--]]

-- local imports
local ReAction = ReAction
local L = ReAction.L
local _G = _G
local InCombatLockdown = InCombatLockdown

-- module declaration
local moduleID = "State"
local module = ReAction:NewModule( moduleID, "AceEvent-3.0" )

-- Utility --

-- traverse a table tree by key list and fetch the result or first nil
local function tfetch(t, ...)
  for i = 1, select('#', ...) do
    t = t and t[select(i, ...)]
  end
  return t
end

-- traverse a table tree by key list and build tree as necessary
local function tbuild(t, ...)
  for i = 1, select('#', ...) do
    local key = select(i, ...)
    if not t[key] then t[key] = { } end
    t = t[key]
  end
  return t
end

-- PRIVATE --
local InitRules, ApplyStates
do
  local ruleformats = { }

  function InitRules()
    local forms = { }
    for i = 1, GetNumShapeshiftForms() do
      local icon = GetShapeshiftFormInfo(i)
      forms[icon] = i;
    end
      -- sort by icon since it's locale-independent
      -- use 9 if not found since 9 is never a valid stance/form
      -- we do these shenanigans instead of hardcoding the stances because
      -- the ordering varies if the character is missing a form. For warriors
      -- this is rarely a problem but for druids it can be. Some people never bother
      -- to do the aquatic form quest, and stance 5 can be either flight or tree/boomkin
      -- depending on talents.
    local defensive = forms["Interface\\Icons\\Ability_Warrior_DefensiveStance"] or 9
    local berserker = forms["Interface\\Icons\\Ability_Racial_Avatar"] or 9
    local bear      = forms["Interface\\Icons\\Ability_Racial_BearForm"] or 9 -- bear and dire bear share the same icon
    local aquatic   = forms["Interface\\Icons\\Ability_Druid_AquaticForm"] or 9
    local cat       = forms["Interface\\Icons\\Ability_Druid_CatForm"] or 9
    local travel    = forms["Interface\\Icons\\Ability_Druid_TravelForm"] or 9
    local treekin   = forms["Interface\\Icons\\Ability_Druid_TreeofLife"] or forms["Interface\\Icons\\Spell_Nature_ForceOfNature"] or 9
    local flight    = forms["Interface\\Icons\\Ability_Druid_FlightForm"] or 9 -- both flight and swift flight share the same icon

    -- As far as I can tell the macro clauses are NOT locale-specific.
    ruleformats.battle        = "stance:1"
    ruleformats.defensive     = ("stance:%d"):format(defensive)
    ruleformats.berserker     = ("stance:%d"):format(berserker)
    ruleformats.caster        = ("form:0/%d/%d/%d"):format(aquatic, travel, flight)
    ruleformats.bear          = ("form:%d"):format(bear)
    ruleformats.cat           = ("form:%d"):format(cat)
    ruleformats.treeOrMoonkin = ("form:%d"):format(treekin)
    ruleformats.stealth       = "stealth"
    ruleformats.nostealth     = "nostealth"
    ruleformats.shadowform    = "form:1"
    ruleformats.noshadowform  = "noform"
    ruleformats.pet           = "pet"
    ruleformats.nopet         = "nopet"
    ruleformats.harm          = "target=target,harm"
    ruleformats.help          = "target=target,help"
    ruleformats.notarget      = "target=target,noexists"
    ruleformats.focusharm     = "target=focus,harm"
    ruleformats.focushelp     = "target=focus,help"
    ruleformats.nofocus       = "target=focus,noexists"
    ruleformats.raid          = "group:raid"
    ruleformats.party         = "group:party"
    ruleformats.solo          = "nogroup"
    ruleformats.combat        = "combat"
    ruleformats.nocombat      = "nocombat"
  end

  local function BuildRuleString(states)
    local s = ""
    local default
    local sorted = { }
    for name in pairs(states) do
      table.insert(sorted,name)
    end
    table.sort(sorted, function(lhs, rhs)
        local olhs = tfetch(states[lhs],"rule","order") or 0
        local orhs = tfetch(states[rhs],"rule","order") or 0
        return olhs < orhs
      end)
    for idx, name in ipairs(sorted) do
      local state = states[name]
      local semi = #s > 0 and "; " or ""
      local mode = tfetch(state,"rule","type")
      if mode == "default" then
        default = name
      elseif mode == "custom" then
        if state.rule.custom then
          -- strip out all spaces from the custom rule
          s = ("%s%s%s %s"):format(s, semi, state.rule.custom:gsub("%s",""), name)
        end
      elseif mode == "any" then
        if state.rule.values then
          local clause = ""
          for key, value in pairs(state.rule.values) do
            clause = ("%s[%s]"):format(clause,ruleformats[key])
          end
          if #clause > 0 then
            s = ("%s%s%s %s"):format(s, semi, clause, name)
          end
        end
      elseif mode == "all" then
        if state.rule.values then
          local clause = ""
          for key, value in pairs(state.rule.values) do
            clause = ("%s%s%s"):format(clause,#clause > 0 and "," or "", ruleformats[key])
          end
          if #clause > 0 then
            s = ("%s%s[%s] %s"):format(s, semi, clause, name)
          end
        end
      end
    end
    if default then
      s = ("%s%s%s"):format(s, #s > 0 and "; " or "", default)
    end
    return s
  end

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

  function ApplyStates( bar )
    local states = tfetch(module.db.profile.bars, bar:GetName(), "states")
    if states then
      local frame = bar:GetFrame()
      local string = BuildRuleString(states)
      ReAction:Print("'"..string.."'")
      if string and #string > 0 then
        -- register a handler to set the value of attribute "state-reaction" 
        -- in response to events as per the rule string
        RegisterStateDriver(frame, "reaction", string)
        drivers[bar] = true
        -- register a trivial map for each "statemap-reaction-XXX" to set 'state' to 'XXX'
        for state in pairs(states) do
          frame:SetAttribute(("statemap-reaction-%s"):format(state), state)
        end
      elseif drivers[bar] then
        UnregisterStateDriver(frame, "reaction")
        drivers[bar] = nil
      end
    end
  end
end


-- module event handlers
function module:OnInitialize()
  self.db = ReAction.db:RegisterNamespace( moduleID, 
    {
      profile = { 
        bars = { },
      }
    }
  )

  InitRules()
  self:RegisterEvent("PLAYER_AURAS_CHANGED")

  ReAction:RegisterBarOptionGenerator(self, "GetBarOptions")

  ReAction.RegisterCallback(self, "OnCreateBar","OnRefreshBar")
  ReAction.RegisterCallback(self, "OnRefreshBar")
  ReAction.RegisterCallback(self, "OnEraseBar")
  ReAction.RegisterCallback(self, "OnRenameBar")
  ReAction.RegisterCallback(self, "OnConfigModeChanged")
end

function module:PLAYER_AURAS_CHANGED()
  self:UnregisterEvent("PLAYER_AURAS_CHANGED")
  -- for some classes the number of stances is 0 until this event fires
  InitRules()
end

function module:OnRefreshBar(event, bar, name)
  local c = self.db.profile.bars[name]
  if c then
    self:UpdateStates(bar)
  end
end

function module:OnEraseBar(event, bar, name)
  self.db.profile.bars[name] = nil
end

function module:OnRenameBar(event, bar, oldname, newname)
  local b = self.db.profile.bars
  bars[newname], bars[oldname] = bars[oldname], nil
end

function module:OnConfigModeChanged(event, mode)
  -- TODO: unregister all state drivers (temporarily) and hidestates
end


-- API --

function module:UpdateStates( bar )
  ApplyStates(bar)
end

function module:CreateState( bar, name )
  local states = tbuild(self.db.profile.bars, bar:GetName(), "states")
  if states[name] then
    ReAction:UserError(L["State named '%s' already exists"]:format(name))
  else
    states[name] = { }
  end
end

function module:DeleteState( bar, name )
  local states = tfetch(self.db.profile.bars, bar:GetName(), "states")
  if states[name] then
    states[name] = nil
    ApplyStates(bar)
  end
end

-- Options --

local CreateBarOptions
do
  local function ClassCheck(...)
    for i = 1, select('#',...) do
      local _, c = UnitClass("player")
      if c == select(i,...) then
        return false
      end
    end
    return true
  end

  -- pre-sorted by the order they should appear in
  local rules = {
    --  rule          hidden                          fields
    { "stance",  ClassCheck("WARRIOR"),          { {battle = L["Battle Stance"]}, {defensive = L["Defensive Stance"]}, {berserker = L["Berserker Stance"]} } },
    { "form",    ClassCheck("DRUID"),            { {caster = L["Caster Form"]}, {bear = L["Bear Form"]}, {cat = L["Cat Form"]}, {treeOrMoonkin = L["Tree/Moonkin"]}  } },
    { "stealth", ClassCheck("ROGUE","DRUID"),    { {stealth = L["Stealth"]}, {nostealth = L["No Stealth"]} } },
    { "shadow",  ClassCheck("PRIEST"),           { {shadowform = L["Shadowform"]}, {noshadowform = L["No Shadowform"]} } },
    { "pet",     ClassCheck("HUNTER","WARLOCK"), { {pet = L["With Pet"]}, {nopet = L["Without Pet"]} } },
    { "target",  false,                          { {harm = L["Hostile Target"]}, {help = L["Friendly Target"]}, {notarget = L["No Target"]} } },
    { "focus",   false,                          { {focusharm = L["Hostile Focus"]}, {focushelp = L["Friendly Focus"]}, {nofocus = L["No Focus"]} } },
    { "group",   false,                          { {raid = L["Raid"]}, {party = L["Party"]}, {solo = L["Solo"]} } },
    { "combat",  false,                          { {combat = L["In Combat"]}, {nocombat = L["Out of Combat"]} } },
  }

  local ruleSelect = { }
  local ruleMap    = { }
  local optionMap  = setmetatable({},{__mode="k"})

  -- unpack rules table into ruleSelect and ruleMap
  for _, c in ipairs(rules) do
    local rule, hidden, fields = unpack(c)
    if not hidden then
      for _, field in ipairs(fields) do
        local key, label = next(field)
        table.insert(ruleSelect, label)
        table.insert(ruleMap, key)
      end
    end
  end

  local function CreateStateOptions(bar, name)
    local opts = { 
      type = "group",
      name = name,
      childGroups = "tab",
    }

    local states = tbuild(module.db.profile.bars, bar:GetName(), "states")

    local function put( key, value, ... )
      tbuild(states, opts.name, "rule", ...)[key] = value
    end

    local function fetch( ... )
      return tfetch(states, opts.name, "rule", ...)
    end

    local function fixall(setkey)
      -- if multiple selections in the same group are chosen when 'all' is selected,
      -- keep only one of them. If changing the mode, the first in the fields list will 
      -- be chosen arbitrarily. Otherwise, if selecting a new checkbox from the field-set,
      -- it will be retained.
      local notified = false
      for _, c in ipairs(rules) do
        local rule, hidden, fields = unpack(c)
        local found = false
        for key in ipairs(fields) do
          if fetch("values",key) then
            if (found or setkey) and key ~= setkey then
              put(key,false,"values")
              if not setkey and not notified then
                ReAction:UserError(L["Warning: one or more incompatible rules were turned off"])
                notified = true
              end
            end
            found = true
          end
        end
      end
    end

    local function getNeighbors()
      local before, after
      for k, v in pairs(states) do
        local o = tonumber(tfetch(v, "rule", "order"))
        if o and k ~= opts.name then
          local obefore = tfetch(states,before,"rule","order")
          local oafter  = tfetch(states,after,"rule","order")
          if o < opts.order and (not obefore or obefore < o) then
            before = k
          end
          if o > opts.order and (not oafter or oafter > o) then
            after = k
          end
        end
      end
      return before, after
    end

    local function swapOrder( a, b )
      -- do options table
      local args = optionMap[bar].args
      args[a].order, args[b].order = args[b].order, args[a].order
      -- do profile
      a = tbuild(states, a, "rule")
      b = tbuild(states, b, "rule")
      a.order, b.order = b.order, a.order
    end

    local function update()
      module:UpdateStates(bar)
    end


    opts.order = fetch("order")
    if opts.order == nil then
      -- add after the highest
      opts.order = 100
      for _, state in pairs(states) do
        local x = tonumber(tfetch(state, "rule", "order"))
        if x and x >= opts.order then
          opts.order = x + 1
        end
      end
      put("order",opts.order)
    end

    opts.args = {
      properties = {
        type = "group",
        name = L["Properties"],
        order = 1,
        args = {
          delete = {
            type = "execute",
            name = L["Delete this State"],
            func = function(info) 
                module:DeleteState(bar,opts.name)
                optionMap[bar].args[opts.name] = nil
              end,
            order = -1
          },
          rename = {
            type = "input",
            name = L["Name"],
            order = 1,
            get  = function() return opts.name end,
            set  = function(info, value) 
                     -- check for existing state name
                     if states[value] then
                       L["State named '%s' already exists"]:format(value)
                     end
                     local args = optionMap[bar].args
                     states[value], args[value], states[opts.name], args[opts.name] = states[opts.name], args[opts.name], nil, nil
                     opts.name = value
                     update()
                   end, 
            pattern = "^%w*$",
            usage = L["State names must be alphanumeric without spaces"],
          },
          ordering = {
            type = "group",
            inline = true,
            name = L["Evaluation Order"],
            desc = L["State transitions are evaluated in the order listed:\nMove a state up or down to change the order"],
            order = 2,
            args = {
              up = {
                type  = "execute",
                name  = L["Up"],
                width = "half",
                order = 1,
                func  = function()
                          local before, after = getNeighbors()
                          if before then
                            swapOrder(before, opts.name)
                            update()
                          end
                        end,
              },
              down = {
                type  = "execute",
                name  = L["Down"],
                width = "half",
                order = 2,
                func  = function() 
                          local before, after = getNeighbors()
                          if after then
                            ReAction:Print(opts.name, after)
                            swapOrder(opts.name, after)
                            update()
                          end
                        end,
              }
            }
          },
          -- keybinding for show-this-state would go here
          -- show/hide would go here
          -- page # would go here
          -- anchoring would go here
        }
      },
      rules = {
        type   = "group",
        name   = L["Rules"],
        order  = 2,
        args   = {
          mode = {
            type   = "select",
            style  = "radio",
            name   = L["Select this state"],
            values = { 
              default = L["by default"], 
              any = L["when ANY of these"], 
              all = L["when ALL of these"], 
              custom = L["via custom rule"] 
            },
            set    = function( info, value )
                       put("type", value)
                       fixall()
                       update()
                     end,
            get    = function( info )
                       return fetch("type")
                     end,
            order  = 2
          },
          clear = {
            type     = "execute",
            name     = L["Clear All"],
            func     = function()
                         local type = fetch("type")
                         if type == "custom" then
                           put("custom","")
                         elseif type == "any" or type == "all" then
                           put("values", {})
                         end
                         update()
                       end,
            order    = 3
          },
          inputs = {
            type     = "multiselect",
            name     = L["Rules"],
            hidden   = function()
                         return fetch("type") == "custom"
                       end,
            disabled = function()
                         return fetch("type") == "default"
                       end,
            values   = ruleSelect,
            set      = function(info, key, value )
                         put(ruleMap[key], value or nil, "values")
                         if value then
                           fixall(ruleMap[key])
                         end
                         update()
                       end,
            get      = function(info, key)
                         return fetch("values", ruleMap[key]) or false
                       end,
            order    = 4
          },
          custom = {
            type = "input",
            multiline = true,
            hidden = function()
                       return fetch("type") ~= "custom"
                     end,
            disabled = function()
                         return fetch("type") == "default"
                       end,
            name = L["Custom Rule"],
            desc = L["Syntax like macro rules: see preset rules for examples"],
            set  = function(info, value) 
                     put("custom",value)
                     update()
                   end,
            get  = function(info)
                     return fetch("custom") or ""
                   end,
            validate = function (info, rule)
                local s = rule:gsub("%s","") -- remove all spaces
                -- unfortunately %b and captures don't support the '+' notation, or this would be considerably simpler
                repeat
                  if s == "" then
                    return true
                  end
                  local c, r = s:match("(%b[])(.*)")
                  if c == nil and s and #s > 0 then
                    return L["Invalid custom rule '%s': each clause must appear within [brackets]"]:format(rule)
                  end
                  s = r
                until c == nil
                return true
              end,
            order = 5,
          }
        }
      }
    }
    return opts
  end


  CreateBarOptions = function(bar)
    local private = { }
    local options = {
      type = "group",
      name = L["Dynamic State"],
      childGroups = "tree",
      disabled = InCombatLockdown,
      args = {
        __desc__ = {
          type = "description",
          name = L["States are evaluated in the order they are listed"],
          order = 1
        },
        __new__ = {
          type = "group",
          name = L["New State..."],
          order = 2,
          args = {
            name = {
              type = "input",
              name = L["State Name"],
              desc = L["Set a name for the new state"],
              get = function() return private.newstatename or "" end,
              set = function(info,value) private.newstatename = value end,
              pattern = "^%w*$",
              usage = L["State names must be alphanumeric without spaces"],
              order = 1
            },
            create = {
              type = "execute",
              name = L["Create State"],
              func = function ()
                  local name = private.newstatename
                  module:CreateState(bar,name) -- TODO: select default state options and pass as final argument
                  optionMap[bar].args[name] = CreateStateOptions(bar,name)
                  private.newstatename = ""
                end,
              disabled = function()
                  local name = private.newstatename or ""
                  return #name == 0 or name:find("%W")
                end,
              order = 2,
            }
          }
        }
      }
    }
    local states = tfetch(module.db.profile.bars, bar:GetName(), "states")
    if states then
      for name, config in pairs(states) do
        options.args[name] = CreateStateOptions(bar,name)
      end
    end
    optionMap[bar] = options
    return options
  end
end

function module:GetBarOptions(bar)
  return CreateBarOptions(bar)
end