import json
import os
import subprocess
import time

from amc_server.context import SESSIONS_DIR, ZELLIJ_BIN, ZELLIJ_PLUGIN, _DISMISSED_MAX, _dismissed_codex_ids
from amc_server.logging_utils import LOGGER


class SessionControlMixin:
    _FREEFORM_MODE_SWITCH_DELAY_SEC = 0.30
    _DEFAULT_SUBMIT_ENTER_DELAY_SEC = 0.20

    def _dismiss_session(self, session_id):
        """Delete a session file (manual dismiss from dashboard)."""
        safe_id = os.path.basename(session_id)
        session_file = SESSIONS_DIR / f"{safe_id}.json"
        # Track dismissed Codex sessions to prevent re-discovery
        # Evict oldest entries if set is full (prevents unbounded growth)
        while len(_dismissed_codex_ids) >= _DISMISSED_MAX:
            _dismissed_codex_ids.pop()
        _dismissed_codex_ids.add(safe_id)
        session_file.unlink(missing_ok=True)
        self._send_json(200, {"ok": True})

    def _respond_to_session(self, session_id):
        """Inject a response into the session's Zellij pane."""
        safe_id = os.path.basename(session_id)
        session_file = SESSIONS_DIR / f"{safe_id}.json"

        # Read request body
        try:
            content_length = int(self.headers.get("Content-Length", 0))
            body = json.loads(self.rfile.read(content_length))
            if not isinstance(body, dict):
                self._json_error(400, "Invalid JSON body")
                return
            text = body.get("text", "")
            is_freeform = body.get("freeform", False)
            try:
                option_count = int(body.get("optionCount", 0))
            except (TypeError, ValueError):
                option_count = 0
        except (json.JSONDecodeError, ValueError):
            self._json_error(400, "Invalid JSON body")
            return

        if not isinstance(text, str):
            self._json_error(400, "Missing or empty 'text' field")
            return
        if not text or not text.strip():
            self._json_error(400, "Missing or empty 'text' field")
            return

        # Load session
        if not session_file.exists():
            self._json_error(404, "Session not found")
            return

        try:
            session = json.loads(session_file.read_text())
            if not isinstance(session, dict):
                self._json_error(500, "Failed to read session")
                return
        except (json.JSONDecodeError, OSError):
            self._json_error(500, "Failed to read session")
            return

        zellij_session = session.get("zellij_session", "")
        zellij_pane = session.get("zellij_pane", "")

        if not zellij_session or not zellij_pane:
            self._json_error(400, "Session missing Zellij pane info - cannot send input without a pane target")
            return

        # Parse pane ID from "terminal_N" format
        pane_id = self._parse_pane_id(zellij_pane)
        if pane_id is None:
            self._json_error(400, f"Invalid pane format: {zellij_pane}")
            return

        # For freeform responses, we need two-step injection:
        # 1. Send "Other" option number (optionCount + 1) WITHOUT Enter
        # 2. Wait for Claude Code to switch to text input mode
        # 3. Send the actual text WITH Enter
        if is_freeform and option_count > 0:
            other_num = str(option_count + 1)
            result = self._inject_to_pane(zellij_session, pane_id, other_num, send_enter=False)
            if not result["ok"]:
                self._send_json(500, {"ok": False, "error": f"Failed to activate freeform mode: {result['error']}"})
                return
            # Delay for Claude Code to switch to text input mode
            time.sleep(self._FREEFORM_MODE_SWITCH_DELAY_SEC)

        # Inject the actual text first, then submit with delayed Enter.
        result = self._inject_text_then_enter(zellij_session, pane_id, text)

        if result["ok"]:
            self._send_json(200, {"ok": True})
        else:
            self._send_json(500, {"ok": False, "error": result["error"]})

    def _inject_text_then_enter(self, zellij_session, pane_id, text):
        """Send text and trigger Enter in two steps to avoid newline-only races."""
        result = self._inject_to_pane(zellij_session, pane_id, text, send_enter=False)
        if not result["ok"]:
            return result

        time.sleep(self._get_submit_enter_delay_sec())
        # Send Enter as its own action after the text has landed.
        return self._inject_to_pane(zellij_session, pane_id, "", send_enter=True)

    def _get_submit_enter_delay_sec(self):
        raw = os.environ.get("AMC_SUBMIT_ENTER_DELAY_MS", "").strip()
        if not raw:
            return self._DEFAULT_SUBMIT_ENTER_DELAY_SEC
        try:
            ms = float(raw)
            if ms < 0:
                return 0.0
            if ms > 2000:
                ms = 2000
            return ms / 1000.0
        except ValueError:
            return self._DEFAULT_SUBMIT_ENTER_DELAY_SEC

    def _parse_pane_id(self, zellij_pane):
        """Extract numeric pane ID from various formats."""
        if not zellij_pane:
            return None

        # Try direct integer (e.g., "10")
        try:
            return int(zellij_pane)
        except ValueError:
            pass

        # Try "terminal_N" format
        parts = zellij_pane.split("_")
        if len(parts) == 2 and parts[0] in ("terminal", "plugin"):
            try:
                return int(parts[1])
            except ValueError:
                pass

        return None

    def _inject_to_pane(self, zellij_session, pane_id, text, send_enter=True):
        """Inject text into a pane using zellij actions."""
        env = os.environ.copy()
        env["ZELLIJ_SESSION_NAME"] = zellij_session
        # Best-effort: some zellij actions respect this pane env.
        env["ZELLIJ_PANE_ID"] = f"terminal_{pane_id}"

        # Pane-accurate routing requires the plugin.
        if ZELLIJ_PLUGIN.exists():
            result = self._try_plugin_inject(env, zellij_session, pane_id, text, send_enter)
            if result["ok"]:
                return result
            LOGGER.warning(
                "Plugin injection failed for session=%s pane=%s: %s",
                zellij_session,
                pane_id,
                result.get("error", "unknown error"),
            )
        else:
            LOGGER.warning("Zellij plugin missing at %s", ZELLIJ_PLUGIN)

        # `write-chars` targets whichever pane is focused, which is unsafe for AMC.
        if self._allow_unsafe_write_chars_fallback():
            LOGGER.warning("Using unsafe write-chars fallback (focused pane only)")
            return self._try_write_chars_inject(env, zellij_session, text, send_enter)

        return {
            "ok": False,
            "error": (
                "Pane-targeted injection requires zellij-send-keys plugin; "
                "set AMC_ALLOW_UNSAFE_WRITE_CHARS_FALLBACK=1 to force focused-pane fallback"
            ),
        }

    def _allow_unsafe_write_chars_fallback(self):
        value = os.environ.get("AMC_ALLOW_UNSAFE_WRITE_CHARS_FALLBACK", "").strip().lower()
        return value in ("1", "true", "yes", "on")

    def _try_plugin_inject(self, env, zellij_session, pane_id, text, send_enter=True):
        """Try injecting via zellij-send-keys plugin (no focus change)."""
        payload = json.dumps({
            "pane_id": pane_id,
            "text": text,
            "send_enter": bool(send_enter),
        })

        try:
            result = subprocess.run(
                [
                    ZELLIJ_BIN,
                    "--session",
                    zellij_session,
                    "action",
                    "pipe",
                    "--plugin",
                    f"file:{ZELLIJ_PLUGIN}",
                    "--name",
                    "send_keys",
                    "--floating-plugin",
                    "false",
                    "--",
                    payload,
                ],
                env=env,
                capture_output=True,
                text=True,
                timeout=3,
            )

            if result.returncode == 0:
                return {"ok": True}
            return {"ok": False, "error": result.stderr or "plugin failed"}

        except subprocess.TimeoutExpired:
            return {"ok": False, "error": "plugin timed out"}
        except Exception as e:
            return {"ok": False, "error": str(e)}

    def _try_write_chars_inject(self, env, zellij_session, text, send_enter=True):
        """Inject via write-chars (UNSAFE: writes to focused pane)."""
        try:
            # Write the text
            result = subprocess.run(
                [ZELLIJ_BIN, "--session", zellij_session, "action", "write-chars", text],
                env=env,
                capture_output=True,
                text=True,
                timeout=2,
            )

            if result.returncode != 0:
                return {"ok": False, "error": result.stderr or "write-chars failed"}

            # Send Enter if requested
            if send_enter:
                result = subprocess.run(
                    [ZELLIJ_BIN, "--session", zellij_session, "action", "write", "13"],  # 13 = Enter
                    env=env,
                    capture_output=True,
                    text=True,
                    timeout=2,
                )

                if result.returncode != 0:
                    return {"ok": False, "error": result.stderr or "write Enter failed"}

            return {"ok": True}

        except subprocess.TimeoutExpired:
            return {"ok": False, "error": "write-chars timed out"}
        except FileNotFoundError:
            return {"ok": False, "error": f"zellij not found (resolved binary: {ZELLIJ_BIN})"}
        except Exception as e:
            return {"ok": False, "error": str(e)}