"""Gemini CLI backend."""

import json
import os
import shutil

from tai_pkg.clirun import Cli
from tai_pkg.errors import BackendError
from tai_pkg.opencode import Opencode

__all__ = ["Gemini"]


class Gemini:
    """Gemini."""

    @staticmethod
    def gemini_binary():
        return os.environ.get("GEMINI_BIN") or shutil.which("gemini")

    @staticmethod
    def gemini_parse_output(stdout):
        try:
            data = json.loads(stdout or "")
        except ValueError:
            return Opencode.opencode_parse(stdout)
        if not isinstance(data, dict):
            return Opencode.opencode_parse(stdout)
        err = data.get("error")
        if err:
            raise BackendError("gemini: %s" % (json.dumps(err) if isinstance(err, dict) else str(err))[:300])
        response = data.get("response")
        if isinstance(response, str) and response.strip():
            return Opencode.opencode_parse(response)
        return Opencode.opencode_parse(stdout)

    @staticmethod
    def gemini_run(prompt, timeout):
        binary = Gemini.gemini_binary()
        if not binary:
            raise BackendError("gemini CLI not found (GEMINI_BIN or PATH)")
        base = [binary, "-p", prompt]
        variants = [
            base + ["--output-format", "json", "--approval-mode", "plan"],
            base + ["--output-format", "json"],
            base,
        ]
        last_error = ""
        for argv in variants:
            done = Cli._cli_run(argv, None, timeout, "gemini")
            if done.returncode != 0 and Cli._cli_unknown_flag(done.stderr) and argv is not variants[-1]:
                last_error = (done.stderr or "").strip()[:200]
                continue
            if done.returncode != 0 and not (done.stdout or "").strip():
                blob = ((done.stderr or "") + "\n" + (done.stdout or "")).strip()
                if Cli._cli_auth_failure(blob):
                    raise BackendError("gemini not authenticated (run gemini login or set GEMINI_API_KEY): %s" % blob[:200])
                hint = {42: "input error", 53: "turn limit exceeded"}.get(done.returncode, "")
                raise BackendError("gemini exit %d%s: %s" % (done.returncode, " (%s)" % hint if hint else "", blob[:300] or last_error or "no output"))
            if not (done.stdout or "").strip():
                blob = (done.stderr or "").strip()
                raise BackendError("gemini returned no output: %s" % (blob[:300] or last_error or "empty stdout"))
            return done.stdout or ""
        raise BackendError("gemini failed: %s" % (last_error or "no usable output"))

    @staticmethod
    def gemini_health():
        binary = Gemini.gemini_binary()
        if not binary:
            return "missing: gemini CLI not found"
        return Cli._cli_version_only_health(binary, "gemini")