-- license:BSD-3-Clause
-- Изолированный backend sdbg. Один каталог/процесс-владелец на сессию.
-- Не загружать одновременно с другим мостом управления тем же CPU.
local exports = { name="sdbgbridge", version="0.1.0", description="Sprinter source debugger",
                  license="BSD-3-Clause", author={name="Sprinter C-Compiler contributors"} }
function exports.startplugin()
  local json = require("json")
  local lfs = require("lfs")
  local directory = assert(os.getenv("SDBG_IPC_DIR"), "Нужен SDBG_IPC_DIR")
  local session = assert(os.getenv("SDBG_SESSION_ID"), "Нужен SDBG_SESSION_ID")
  local snapdir = os.getenv("SDBG_SNAP_DIR")
  local snapshot_sequence = 0
  local generation, sequence = 0, 0
  local events, owned = {}, {}
  local state, pending = "initializing", nil
  local invalidated=false
  local session_started=false
  local registers = {"PC","SP","AF","BC","DE","HL","IX","IY","AF2","BC2","DE2","HL2",
                     "I","R","IM","IFF1","IFF2","PG0","PG1","PG2","PG3","CNF","7FFD","1FFD"}
  local function machine() return manager.machine end
  local function cpu() return machine().devices[":maincpu"] end
  local function now()
    local t=machine().time
    return t.seconds+t.attoseconds/1e18
  end
  local function event(kind, body)
    sequence=sequence+1
    events[#events+1]={seq=sequence,kind=kind,generation=generation,body=body or {}}
    if #events>512 then table.remove(events,1) end
  end
  local function atomic(path, value)
    local file=assert(io.open(path..".tmp","wb"))
    file:write(json.stringify(value));file:close()
    assert(os.rename(path..".tmp",path))
  end
  local function update()
    if invalidated then return end
    local observed=machine().debugger.execution_state=="stop" and "stopped" or "running"
    -- step() исполняется лишь после возврата periodic callback.
    if pending and pending.kind:match("^step") and now()<=pending.time then return end
    if observed~=state or (pending and observed=="stopped") then
      state=observed
      generation=generation+1
      local body={pc=cpu().state.PC.value}
      if pending then body.reason=pending.kind end
      event(state,body)
      if state=="stopped" then pending=nil end
    end
  end
  local function stopped(request)
    assert(state=="stopped" and not pending,"CPU не остановлен")
    assert(request.generation==generation,"Устаревшая generation")
  end
  local function number(value, limit)
    assert(type(value)=="number" and value%1==0 and value>=0 and value<=limit,"Недопустимое число")
    return value
  end
  local function first_screen()
    for _,screen in pairs(machine().screens) do return screen end
    error("Экран MAME не найден")
  end
  local function share_info()
    local result={shares={},regions={}}
    for tag,share in pairs(machine().memory.shares) do
      result.shares[#result.shares+1]={tag=tag,size=share.size}
    end
    for tag,region in pairs(machine().memory.regions) do
      result.regions[#result.regions+1]={tag=tag,size=region.size}
    end
    table.sort(result.shares,function(a,b) return a.tag<b.tag end)
    table.sort(result.regions,function(a,b) return a.tag<b.tag end)
    return result
  end
  local function read_share(tag,address,length)
    assert(type(tag)=="string" and #tag>0 and #tag<=128,"Нужен точный tag share")
    local share=machine().memory.shares[tag]
    assert(share,"Share не найден: "..tag)
    local size=number(share.size,0x10000000)
    address=number(address,size)
    length=number(length,4096)
    assert(length>=1 and address+length<=size,"Чтение за пределами share")
    local bytes={}
    for offset=0,length-1 do
      bytes[#bytes+1]=string.format("%02x",share:read_u8(address+offset))
    end
    return {tag=tag,address=address,length=length,size=size,hex=table.concat(bytes),
            generation=generation}
  end
  local invalidate
  local function dispatch(request)
    assert(request.session==session,"Чужая сессия")
    local args=request.args or {}
    local command=request.command
    if invalidated and command~="hello" and command~="snapshot" and command~="events" then
      error("Сессия инвалидирована reset/load")
    end
    if command=="hello" then
      session_started=true
      return {protocol=1,session=session,capabilities={snapshot=true,memory=true,
              instruction_step=true,step_over=true,step_out=true,
              bank_guard=true,deferred_breakpoints=true,console_print=true,
              shares=true,screen_pixels=true,screen_snapshot=snapdir~=nil,
              program_memory=true,list_ports=true,disassemble_logical=true},state=state}
    elseif command=="snapshot" then
      local result={state=state,time=now(),paused=machine().paused}
      local screen=first_screen()
      result.frame=screen:frame_number()
      result.keyboards=setmetatable({}, {__jsontype="object"})
      for tag,kbd in pairs(machine().natkeyboard.keyboards) do
        result.keyboards[tag]=kbd.enabled
      end
      if state=="stopped" and not pending then
        result.registers=setmetatable({}, {__jsontype="object"})
        for _,name in ipairs(registers) do
          if cpu().state[name] then result.registers[name]=cpu().state[name].value end
        end
      end
      return result
    elseif command=="key" then
      -- Этот путь нужен для воспроизводимых UI-тестов; обычная клавиатура
      -- хоста остаётся у MAME и не проходит через bridge.
      assert(state=="running" or (state=="stopped" and args.down==false),
             "Нажатие принимается при running CPU, отпускание также при stopped")
      local tag=args.tag
      assert(type(tag)=="string" and tag:match("^:kbd:ms_naturl:P%d+%.%d+$"),
             "Разрешены только порты PC-клавиатуры Sprinter")
      local mask=number(args.mask,0xffff)
      assert(type(args.down)=="boolean","Нужен флаг down")
      local port=machine().ioport.ports[tag]
      assert(port,"Порт клавиатуры не найден")
      for _,field in pairs(port.fields) do
        if field.mask==mask then
          field:set_value(args.down and 1 or 0)
          return {accepted=true,tag=tag,mask=mask,down=args.down}
        end
      end
      error("Поле клавиатуры не найдено")
    elseif command=="events" then
      local result={events={},last=sequence,first=events[1] and events[1].seq or sequence+1}
      for _,item in ipairs(events) do
        if item.seq>(args.after or 0) then result.events[#result.events+1]=item end
      end
      return result
    elseif command=="console_tail" then
      local log=machine().debugger.consolelog
      local total=#log
      local count=number(args.count or 40,200)
      local lines={}
      for index=math.max(1,total-count+1),total do
        lines[#lines+1]=log[index]
      end
      return {total=total,lines=lines}
    elseif command=="pause" then
      if state~="stopped" then
        pending={kind="pause",time=now()}
        machine().debugger.execution_state="stop"
      end
      return {accepted=true}
    elseif command=="continue" or command=="step" or command=="step_over" or
           command=="step_out" then
      stopped(request)
      generation=generation+1
      state="running"
      event("running",{reason=command})
      if command=="step" then
        local count=number(args.count or 1,64)
        assert(count>=1,"step count должен быть 1..64")
        pending={kind="step",time=now()}
        cpu().debug:step(count)
      elseif command=="step_over" then
        local count=number(args.count or 1,64)
        assert(count>=1,"over count должен быть 1..64")
        pending={kind="step_over",time=now()}
        -- В консоли MAME числа без префикса шестнадцатеричные.
        machine().debugger:command("over #"..count)
      elseif command=="step_out" then
        pending={kind="step_out",time=now()}
        machine().debugger:command("out")
      else machine().debugger.execution_state="run" end
      return {accepted=true}
    elseif command=="memory" then
      stopped(request)
      local address=number(args.address,0xffff)
      assert(args.enabled==nil or type(args.enabled)=="boolean","Неверный enabled")
      local length=number(args.length,4096)
      assert(address+length<=0x10000,"Чтение за пределами logical memory")
      local symbols=emu.symbol_table(cpu())
      local bytes={}
      for offset=0,length-1 do
        -- Этот интерфейс отключает side effects в отличие от space:read_u8.
        bytes[#bytes+1]=string.format("%02x",symbols:memory_value(":maincpu","p",address+offset,1,true))
      end
      return {hex=table.concat(bytes)}
    elseif command=="program_memory" then
      stopped(request)
      local address=number(args.address,0x3ffff)
      local length=number(args.length,4096)
      assert(length>=1 and address+length<=0x40000,
             "Чтение за пределами raw program space")
      local symbols=emu.symbol_table(cpu())
      local bytes={}
      for offset=0,length-1 do
        bytes[#bytes+1]=string.format("%02x",symbols:memory_value(
          ":maincpu","p",address+offset,1,true))
      end
      return {space="program",address=address,length=length,
              hex=table.concat(bytes),generation=generation}
    elseif command=="disassemble_logical" then
      stopped(request)
      local address=number(args.address,0xffff)
      local length=number(args.length,256)
      assert(length>=1 and address+length<=0x10000,
             "Дизассемблирование за пределами logical Z80")
      local path=directory.."/_disasm.txt"
      os.remove(path) -- Не возвращать файл от прежней команды при ошибке MAME.
      machine().debugger:command(string.format("dasm %s,0x%X,#%d",path,address,length))
      local size=lfs.attributes(path,"size")
      assert(size and size>0 and size<=65536,"MAME не создал ограниченный disasm-файл")
      local file=assert(io.open(path,"rb"))
      local output=file:read("*a")
      file:close()
      os.remove(path)
      return {space="logical_z80",address=address,length=length,
              text=output,generation=generation}
    elseif command=="list_ports" then
      local result={ports={},truncated=false}
      local fields_seen=0
      for tag,port in pairs(machine().ioport.ports) do
        if #result.ports>=512 then result.truncated=true;break end
        local item={tag=tag,fields={}}
        for name,field in pairs(port.fields) do
          if fields_seen>=4096 then result.truncated=true;break end
          item.fields[#item.fields+1]={name=tostring(name),mask=field.mask}
          fields_seen=fields_seen+1
        end
        table.sort(item.fields,function(a,b) return a.mask<b.mask end)
        result.ports[#result.ports+1]=item
      end
      table.sort(result.ports,function(a,b) return a.tag<b.tag end)
      return result
    elseif command=="list_shares" then
      return share_info()
    elseif command=="read_share" then
      return read_share(args.tag,args.address,args.length)
    elseif command=="read_vram" then
      local matches={}
      for tag in pairs(machine().memory.shares) do
        if tag:find("vram",1,true) then matches[#matches+1]=tag end
      end
      assert(#matches==1,"Нужен ровно один VRAM share; используйте list_shares")
      return read_share(matches[1],args.address,args.length)
    elseif command=="screen_pixels" then
      local x=number(args.x,4095)
      local y=number(args.y,4095)
      local width=number(args.width,512)
      local height=number(args.height,512)
      assert(width>=1 and height>=1 and width*height<=8192,
             "Прямоугольник должен содержать 1..8192 пикселей")
      local screen=first_screen()
      local values={}
      for dy=0,height-1 do
        for dx=0,width-1 do
          values[#values+1]=string.format("%04X",screen:pixel(x+dx,y+dy)&0xffff)
        end
      end
      return {x=x,y=y,width=width,height=height,format="pen16be-hex",
              hex=table.concat(values),frame=screen:frame_number(),
              emulated_time=now(),stale_frame=state=="stopped",generation=generation}
    elseif command=="screen_snapshot" then
      assert(snapdir and #snapdir>0,"Каталог снимков не настроен")
      snapshot_sequence=snapshot_sequence+1
      local screen=first_screen()
      local path=string.format("%s/sdbg_%06d.png",snapdir,snapshot_sequence)
      local err=screen:snapshot(path)
      assert(err==nil,"Снимок не создан: "..tostring(err))
      local size=lfs.attributes(path,"size")
      assert(size and size>0 and size<=8388608,"Неверный размер снимка")
      return {path=path,size=size,format="png",frame=screen:frame_number(),
              emulated_time=now(),stale_frame=state=="stopped",generation=generation}
    elseif command=="console_print" then
      stopped(request)
      local text=args.text
      assert(type(text)=="string" and #text>=1 and #text<=2048,
             "Нужна строка журнала до 2048 байт")
      -- В debugger printf уже отформатированный текст — только данные.
      -- Убираем управляющие символы и экранируем синтаксис команды/формата.
      local safe=text:gsub("[%c]"," "):gsub("\\","\\\\")
                     :gsub("%%","%%%%"):gsub('"',"'")
      machine().debugger:command('printf "'..safe..'"')
      return {printed=true}
    elseif command=="breakpoint" then
      stopped(request)
      local address=number(args.address,0xffff)
      local condition=""
      if args.window~=nil or args.page~=nil then
        local window=number(args.window,3)
        local page=number(args.page,255)
        local ports={[0]=0x82,[1]=0xa2,[2]=0xc2,[3]=0xe2}
        -- Дополнительные PG state entries драйвера Sprinter не входят в
        -- expression table CPU. Читаем штатный page-port без side effects;
        -- числа debugger expression по умолчанию шестнадцатеричные.
        condition=string.format("ib@%x==%x",ports[window],page)
      end
      local id=cpu().debug:bpset(address,condition,"")
      owned[id]={address=address,condition=condition}
      if args.enabled==false then cpu().debug:bpdisable(id) end
      return {id=id,condition=condition,enabled=args.enabled~=false}
    elseif command=="activate_breakpoints" then
      stopped(request)
      local count=0
      for id in pairs(owned) do
        if cpu().debug:bpenable(id) then count=count+1 end
      end
      return {enabled=count}
    elseif command=="deactivate_breakpoints" then
      stopped(request)
      local count=0
      for id in pairs(owned) do
        if cpu().debug:bpdisable(id) then count=count+1 end
      end
      return {disabled=count}
    elseif command=="clear" then
      -- Удаление точки безопасно и при running: callback исполняется на
      -- потоке MAME, а MCP должен очищать свои точки при закрытии stdio.
      local id=number(args.id,0x7fffffff)
      assert(owned[id],"Точка не принадлежит sdbg")
      cpu().debug:bpclear(id);owned[id]=nil
      return {cleared=id}
    else error("Неподдержанная команда: "..tostring(command)) end
  end
  invalidate=function(reason)
    if invalidated then return end
    if not session_started then return end
    if reason=="state_load" then
      for id in pairs(owned) do cpu().debug:bpclear(id) end
    end
    owned={}
    invalidated=true
    generation=generation+1
    pending=nil
    state="invalidated"
    event("invalidated",{reason=reason})
  end
  -- Subscription-объекты надо удерживать: иначе Lua GC снимет callback.
  exports._subscriptions={
    emu.add_machine_reset_notifier(function() invalidate("reset") end),
    emu.add_machine_post_load_notifier(function() invalidate("state_load") end)
  }
  emu.register_periodic(function()
    if not machine() or not machine().debugger then return end
    update()
    for name in lfs.dir(directory) do
      local id=name:match("^req_(%d+)%.json$")
      if id then
        local path=directory.."/"..name
        local file=io.open(path,"rb")
        if file then
          local data=file:read("*a");file:close()
          local ok,request=pcall(json.parse,data)
          local result
          if ok and type(request)=="table" then ok,result=pcall(dispatch,request)
          else result="Неверный JSON";ok=false end
          atomic(directory.."/resp_"..id..".json",{ok=ok,generation=generation,
                 result=ok and result or nil,error=not ok and tostring(result) or nil,session=session})
          os.remove(path)
        end
      end
    end
  end)
end
return exports