-- Bagshui CPU Profile
-- Exposes: Bagshui.components.CpuProfile
--
-- `/bs cpu` reads ClassicAPI's script profiler and prints where CPU time went since the last
-- reset (or /reload): the busiest addons, Bagshui's busiest frames, and Bagshui's busiest
-- functions. `/bs cpu reset` starts a new measurement.
--
-- Needs ClassicAPI and the scriptProfile CVar (`/console scriptProfile 1`, then /reload).
-- Profiling slows every addon down a little, so turn it off again when done.

Bagshui:AddComponent(function()
  local CpuProfile = {}
  Bagshui.components.CpuProfile = CpuProfile

  local TOP_ADDONS = 5
  local TOP_FRAMES = 4
  local TOP_FUNCTIONS = 8

  --- Print one line to chat with a consistent prefix.
  local function Out(text)
    _G.DEFAULT_CHAT_FRAME:AddMessage("|cffdb4e97Bagshui CPU|r " .. text)
  end

  --- Format milliseconds for display.
  local function Ms(ms)
    if ms >= 1000 then
      return string.format("%.2fs", ms / 1000)
    end
    return string.format("%dms", math.floor(ms + 0.5))
  end

  --- Is the profiler available and switched on?
  ---@return boolean
  function CpuProfile:IsActive()
    if type(_G.GetFunctionCPUUsage) ~= "function" or type(_G.UpdateAddOnCPUUsage) ~= "function" then
      return false
    end
    local ok, value = pcall(_G.GetCVar, "scriptProfile")
    return ok and tostring(value) == "1"
  end

  --- Sort helper: biggest `ms` first.
  local function ByMs(a, b)
    return a.ms > b.ms
  end

  --- CPU time per addon since the last reset.
  ---@return table list { name, ms }
  local function AddOnUsage()
    local list = {}
    pcall(_G.UpdateAddOnCPUUsage)
    for i = 1, _G.GetNumAddOns() do
      local name = _G.GetAddOnInfo(i)
      local ok, ms = pcall(_G.GetAddOnCPUUsage, i)
      if ok and type(ms) == "number" and ms > 0 then
        table.insert(list, { name = name, ms = ms })
      end
    end
    table.sort(list, ByMs)
    return list
  end

  --- CPU time of Bagshui's own frames (scripts on the frame and its children).
  ---@return table list { name, ms }
  local function FrameUsage()
    local list = {}
    if type(_G.GetFrameCPUUsage) ~= "function" then
      return list
    end
    local function Add(name, frame)
      if frame then
        local ok, ms = pcall(_G.GetFrameCPUUsage, frame, true)
        if ok and type(ms) == "number" and ms > 0 then
          table.insert(list, { name = name, ms = ms })
        end
      end
    end
    Add("Event frame", Bagshui.eventFrame)
    for name, component in pairs(Bagshui.components) do
      if type(component) == "table" and type(component.uiFrame) == "table" then
        Add(name .. " window", component.uiFrame)
      end
    end
    table.sort(list, ByMs)
    return list
  end

  --- CPU time of every function reachable from Bagshui's tables.
  --- `total` includes the functions it calls; `self` is time spent in the function itself.
  ---@return table byTotal, table bySelf  Lists of { name, ms }.
  local function FunctionUsage()
    local seen = {}
    local byTotal, bySelf = {}, {}

    local function Scan(prefix, tbl)
      if type(tbl) ~= "table" then
        return
      end
      for key, value in pairs(tbl) do
        if type(value) == "function" and type(key) == "string" and not seen[value] then
          seen[value] = true
          local okTotal, total = pcall(_G.GetFunctionCPUUsage, value, true)
          local okSelf, own = pcall(_G.GetFunctionCPUUsage, value, false)
          local name = prefix .. key
          if okTotal and type(total) == "number" and total > 0 then
            table.insert(byTotal, { name = name, ms = total })
          end
          if okSelf and type(own) == "number" and own > 0 then
            table.insert(bySelf, { name = name, ms = own })
          end
        end
      end
    end

    -- Prototypes first, so shared methods are named after the class that defines them.
    for name, prototype in pairs(Bagshui.prototypes) do
      Scan(name .. ":", prototype)
    end
    for name, component in pairs(Bagshui.components) do
      Scan(name .. ":", component)
    end
    Scan("Bagshui:", Bagshui)
    Scan("BsUtil.", BsUtil)

    table.sort(byTotal, ByMs)
    table.sort(bySelf, ByMs)
    return byTotal, bySelf
  end

  --- Print up to `count` entries of `list`, prefixed by `heading`.
  local function PrintTop(heading, list, count)
    if table.getn(list) == 0 then
      return
    end
    local parts = {}
    for i = 1, math.min(count, table.getn(list)) do
      table.insert(parts, list[i].name .. " " .. Ms(list[i].ms))
    end
    Out("|cffffd100" .. heading .. ":|r " .. table.concat(parts, ", "))
  end

  --- Print the report.
  function CpuProfile:Report()
    if not self:IsActive() then
      Out("profiling is off. Type |cffffffff/console scriptProfile 1|r and |cffffffff/reload|r (needs ClassicAPI).")
      return
    end

    local since = self.resetAt and string.format("%.0fs", _G.GetTime() - self.resetAt) or "the last /reload"
    Out("CPU time since " .. since .. " (/bs cpu reset to start over)")

    PrintTop("Addons", AddOnUsage(), TOP_ADDONS)
    PrintTop("Bagshui frames", FrameUsage(), TOP_FRAMES)
    local byTotal, bySelf = FunctionUsage()
    PrintTop("Bagshui functions, own time", bySelf, TOP_FUNCTIONS)
    PrintTop("Bagshui functions, including calls", byTotal, TOP_FUNCTIONS)
  end

  --- Start a new measurement.
  function CpuProfile:Reset()
    if not self:IsActive() then
      self:Report()
      return
    end
    pcall(_G.ResetCPUUsage)
    self.resetAt = _G.GetTime()
    Out("counters reset. Reproduce the hitch, then type /bs cpu.")
  end

  BsSlash:AddHandler("CPU", function(tokens)
    if tokens[2] and string.lower(tokens[2]) == "reset" then
      CpuProfile:Reset()
    else
      CpuProfile:Report()
    end
  end, true)
end)