// Package proto describes the wire messages shared by the server and the agent.
//
// All agent<->server traffic is plain JSON over HTTP(S) long-polling so it
// survives NAT and restrictive egress firewalls: the agent only ever makes
// outbound requests.
package proto

import "encoding/json"

// Control poll message types (server -> agent, returned from /api/agent/poll).
const (
	// CtrlIdle is returned when the long-poll times out with nothing to do.
	CtrlIdle = "idle"
	// CtrlOpenTerminal tells the agent to spawn a PTY for the session id.
	CtrlOpenTerminal = "open_terminal"
	// CtrlOpenForward tells the agent to dial 127.0.0.1:Port and bridge it to
	// the session id (reverse TCP port-forward).
	CtrlOpenForward = "open_forward"
	// CtrlTask tells the agent to fetch and run the one-shot task TaskID.
	CtrlTask = "task"
)

// EnrollRequest is sent once by a freshly installed agent.
type EnrollRequest struct {
	Name     string `json:"name"`
	Hostname string `json:"hostname"`
	OS       string `json:"os"`
	Arch     string `json:"arch"`
	Version  string `json:"version"`
	User     string `json:"user,omitempty"` // OS user the agent runs as
}

// EnrollResponse carries the identity the agent persists and uses from then on.
type EnrollResponse struct {
	AgentID string `json:"agent_id"`
	Token   string `json:"token"`
}

// ControlMessage is the body returned by the control long-poll.
type ControlMessage struct {
	Type      string `json:"type"`
	SessionID string `json:"session_id,omitempty"`
	Port      int    `json:"port,omitempty"`    // CtrlOpenForward: client-side port to dial
	TaskID    string `json:"task_id,omitempty"` // CtrlTask
	User      string `json:"user,omitempty"`    // CtrlOpenTerminal: OS user for the shell ("" = the agent's own)
}

// Terminal / stream frame types on the session "in" channel (server -> agent).
// Reused for both PTY terminals and raw TCP port-forward streams.
const (
	FrameStdin  = "stdin"  // base64 bytes for the PTY / socket
	FrameResize = "resize" // PTY window size (terminal only)
	FrameClose  = "close"  // tear the stream down
)

// InFrame is one element of the stream downstream batch (server -> agent).
type InFrame struct {
	Type string `json:"type"`
	Data string `json:"data,omitempty"` // base64 bytes
	Cols uint16 `json:"cols,omitempty"`
	Rows uint16 `json:"rows,omitempty"`
}

// InBatch is the JSON body returned by GET /api/agent/term/{sid}/in.
type InBatch struct {
	Frames []InFrame `json:"frames"`
}

// OutMessage is POSTed by the agent to /api/agent/term/{sid}/out.
type OutMessage struct {
	Data string `json:"data,omitempty"` // base64 bytes
	Exit bool   `json:"exit,omitempty"`
}

// --- one-shot tasks (file manager, native in the agent) ---

const (
	TaskFSList     = "fs.list"     // list a directory
	TaskFSRead     = "fs.read"     // read file content (for view/edit)
	TaskFSWrite    = "fs.write"    // write/overwrite file (edit save, create, upload)
	TaskFSMkdir    = "fs.mkdir"    // create directory
	TaskFSDelete   = "fs.delete"   // delete a single file or empty dir
	TaskFSDelTree  = "fs.deltree"  // recursively delete a directory
	TaskFSUnzip    = "fs.unzip"    // unzip an archive (needs `unzip` on the client)
	TaskFSZip      = "fs.zip"      // zip selected paths (native archive/zip)
	TaskFSMove     = "fs.move"     // move/rename
	TaskFSDownload = "fs.download" // read a whole file (larger cap) for browser download

	TaskSysUpdate  = "sys.update"  // download the latest agent binary and restart
	TaskSysUsers   = "sys.users"   // report the agent's user and the login-capable users
	TaskSysUserAdd = "sys.useradd" // create a new OS user
	TaskSysStat    = "sys.stat"    // CPU load, RAM and disk usage right now
	TaskSysSpeed   = "sys.speed"   // measure the link to the server (ping, down, up)
)

// FSReadCap bounds how many bytes TaskFSRead returns (5 MiB). The panel lets a
// file be edited only when it fits, so that a save never cuts it short.
const FSReadCap = 5 * 1024 * 1024

// TaskEnvelope is what the agent fetches for a task id.
type TaskEnvelope struct {
	Type string          `json:"type"`
	Args json.RawMessage `json:"args"`
}

// TaskResult is POSTed back by the agent.
type TaskResult struct {
	OK    bool            `json:"ok"`
	Error string          `json:"error,omitempty"`
	Data  json.RawMessage `json:"data,omitempty"`
}

// fs task argument shapes.
type FSPathArgs struct {
	Path string `json:"path"`
}
type FSWriteArgs struct {
	Path string `json:"path"`
	Data string `json:"data"` // base64 content
}
type FSUnzipArgs struct {
	Path string `json:"path"`
	Dest string `json:"dest"`
}
type FSZipArgs struct {
	Paths []string `json:"paths"`
	Dest  string   `json:"dest"`
}
type FSMoveArgs struct {
	Src string `json:"src"`
	Dst string `json:"dst"`
}

// FSEntry is one directory entry.
type FSEntry struct {
	Name  string `json:"name"`
	IsDir bool   `json:"is_dir"`
	Size  int64  `json:"size"`
	Mode  string `json:"mode"`
	MTime int64  `json:"mtime"`
}

// FSListResult is returned for TaskFSList.
type FSListResult struct {
	Path    string    `json:"path"`
	Entries []FSEntry `json:"entries"`
}

// FSReadResult is returned for TaskFSRead.
type FSReadResult struct {
	Path      string `json:"path"`
	Size      int64  `json:"size"`
	Content   string `json:"content"` // base64
	Truncated bool   `json:"truncated"`
	Binary    bool   `json:"binary"`
}

// SysUsersResult is returned for TaskSysUsers.
type SysUsersResult struct {
	Current   string   `json:"current"`    // user the agent runs as
	CanSwitch bool     `json:"can_switch"` // agent is root, so it can open shells as (and create) other users
	Users     []string `json:"users"`
}

// SysUserAddArgs are the arguments of TaskSysUserAdd.
type SysUserAddArgs struct {
	Name     string `json:"name"`
	Password string `json:"password,omitempty"` // empty leaves the account without a password
	Sudo     bool   `json:"sudo"`               // add to the sudo/wheel group
}

// SysStatResult is returned for TaskSysStat. Sizes are in bytes.
type SysStatResult struct {
	CPU       float64 `json:"cpu"` // load across all cores, 0..100
	NCPU      int     `json:"ncpu"`
	MemTotal  uint64  `json:"mem_total"`
	MemUsed   uint64  `json:"mem_used"`
	DiskTotal uint64  `json:"disk_total"` // filesystem holding "/"
	DiskFree  uint64  `json:"disk_free"`
}

// SysSpeedArgs are the arguments of TaskSysSpeed.
type SysSpeedArgs struct {
	// Relay makes the agent use the relayed streams, which the server pipes
	// to and from the browser.
	Relay bool `json:"relay,omitempty"`
}

// SysSpeedResult is returned for TaskSysSpeed: the agent's HTTP link to the
// server as the agent measured it. Down is server -> agent.
type SysSpeedResult struct {
	PingMs  float64 `json:"ping_ms"`
	DownBps float64 `json:"down_bps"` // bits per second
	UpBps   float64 `json:"up_bps"`
	Relay   bool    `json:"relay,omitempty"` // the streams went through the relay
}