"""Shared renderers for session export commands.

The CLI, dashboard, and slash-command surfaces all deal with the same session-shaped data: a session
dict with a ``messages`` list. Keep filtering and human-readable rendering here so each surface only
has to load sessions and write bytes.
"""

from __future__ import annotations

from datetime import datetime, timezone
from html import escape as html_escape
import json
from typing import Any, Dict, Iterable, Iterator, List, Literal, Optional, Tuple


ExportFormat = Literal["jsonl", "markdown"]
ExportOnly = Literal["user-prompts"]


def normalize_export_format(fmt: str) -> ExportFormat:
    """Return the canonical export format name."""
    value = {"jsonl": "jsonl", "markdown": "markdown", "md": "markdown"}.get((fmt or "jsonl").strip().lower())
    if value is None:
        raise ValueError(f"Unsupported session export format: {fmt}")
    return value  # type: ignore[return-value]


def normalize_export_only(only: Optional[str]) -> Optional[ExportOnly]:
    """Return the canonical export filter name."""
    if only is None:
        return None
    if only.strip().lower() in {"user", "prompts", "user-prompts", "user_prompts"}:
        return "user-prompts"
    raise ValueError(f"Unsupported session export filter: {only}")


def render_sessions_export(
    sessions: Iterable[Dict[str, Any]],
    *,
    fmt: str = "jsonl",
    only: Optional[str] = None,
) -> str:
    """Render exported sessions in a stable, reusable format.

    ``fmt=jsonl`` with no filter intentionally preserves the legacy shape: one full session object
    per line. ``only=user-prompts`` switches the unit of export to one prompt record per line so the
    output is easy to pipe into review, memory-ingestion, or prompt-library tooling.
    """
    session_list = list(sessions)
    export_format = normalize_export_format(fmt)
    export_only = normalize_export_only(only)

    prompts_only = export_only == "user-prompts"
    if export_format == "jsonl":
        rows = iter_user_prompt_records(session_list) if prompts_only else session_list
        lines = [json.dumps(row, ensure_ascii=False) for row in rows]
        return ("\n".join(lines) + "\n") if lines else ""
    if prompts_only:
        return _render_user_prompts_markdown(session_list)
    return _render_full_markdown(session_list)


def export_record_count(
    sessions: Iterable[Dict[str, Any]], *, only: Optional[str] = None
) -> Tuple[int, str]:
    """Return ``(count, noun)`` for status messages after an export."""
    session_list = list(sessions)
    if normalize_export_only(only) == "user-prompts":
        return sum(1 for _ in iter_user_prompt_records(session_list)), "prompt"
    return len(session_list), "session"


def iter_user_prompt_records(
    sessions: Iterable[Dict[str, Any]]
) -> Iterator[Dict[str, Any]]:
    """Yield one normalized record for each user-authored prompt."""
    for session in sessions:
        session_id = str(session.get("id") or session.get("session_id") or "")
        index = 0
        for message in _messages(session):
            if message.get("role") != "user":
                continue
            index += 1
            record: Dict[str, Any] = {
                "session_id": session_id,
                "index": index,
                "created_at": _format_timestamp(message.get("timestamp")),
                "role": "user",
                "text": _message_text(message.get("content")),
            }
            message_id = message.get("id")
            if message_id is not None:
                record["message_id"] = message_id
            event_id = message.get("platform_message_id") or message.get("event_id")
            if event_id:
                record["event_id"] = event_id
            yield record


def _render_user_prompts_markdown(sessions: List[Dict[str, Any]]) -> str:
    lines = _render_sessions_markdown(
        sessions, "User prompts export",
        lambda session: f"User prompts for session {_heading_text(_session_id(session))}",
        lambda session: f"Session {_heading_text(_session_id(session))}",
        _append_prompt_records,
    )
    if not sessions:
        lines += ["_No user prompts found._", ""]
    return _finish_markdown(lines)


def _render_sessions_markdown(sessions, multi_title, single_heading, multi_heading, append_body) -> List[str]:
    """One session → its own H1 with body at H2; several → a shared H1, each session H2/H3."""
    lines: List[str] = []
    if len(sessions) == 1:
        session = sessions[0]
        lines += [f"# {single_heading(session)}", *_session_metadata_lines(session), ""]
        append_body(lines, session, heading_level=2)
    else:
        lines += [f"# {multi_title}", ""]
        for session in sessions:
            lines += [f"## {multi_heading(session)}", *_session_metadata_lines(session), ""]
            append_body(lines, session, heading_level=3)
    return lines


def _append_prompt_records(
    lines: List[str], session: Dict[str, Any], *, heading_level: int
) -> None:
    prompts = list(iter_user_prompt_records([session]))
    if not prompts:
        lines += ["_No user prompts found._", ""]
        return
    marker = "#" * heading_level
    for prompt in prompts:
        timestamp = prompt.get("created_at") or "timestamp unavailable"
        lines.append(f"{marker} {prompt['index']}. {timestamp}")
        if (message_id := prompt.get("message_id")) is not None:
            lines += [f"Message ID: `{message_id}`", ""]
        lines += [str(prompt.get("text") or ""), ""]


def _render_full_markdown(sessions: List[Dict[str, Any]]) -> str:
    return _finish_markdown(_render_sessions_markdown(
        sessions, "Hermes sessions export",
        lambda session: f"Session: {_heading_text(_session_title_or_id(session))}",
        lambda session: f"Session: {_heading_text(_session_title_or_id(session))}",
        _append_session_messages,
    ))


def _append_session_messages(
    lines: List[str], session: Dict[str, Any], *, heading_level: int
) -> None:
    marker = "#" * heading_level
    visible_messages = [
        message for message in _messages(session) if message.get("role") != "system"
    ]
    if not visible_messages:
        lines += ["_No messages found._", ""]
        return

    for message in visible_messages:
        role = str(message.get("role") or "unknown")
        timestamp = _format_timestamp(message.get("timestamp"))
        suffix = f" - {timestamp}" if timestamp else ""
        text = _message_text(message.get("content"))
        if role == "tool":
            tool_name = str(message.get("tool_name") or message.get("name") or "tool")
            lines += [
                f"{marker} Tool: {_heading_text(tool_name)}{suffix}", "",
                f"<details><summary>{html_escape(tool_name)}</summary>", "",
                _fenced_text(text), "", "</details>", "",
            ]
            continue
        label = {"user": "User", "assistant": "Assistant"}.get(role, role.title())
        lines += [f"{marker} {label}{suffix}", "", text, ""]


def _messages(session: Dict[str, Any]) -> List[Dict[str, Any]]:
    messages = session.get("messages") or []
    return [message for message in messages if isinstance(message, dict)]


def _message_text(content: Any) -> str:
    if content is None:
        return ""
    if isinstance(content, list):
        return "\n".join(part for part in map(_content_part_text, content) if part)
    return _content_part_text(content)


def _content_part_text(part: Any) -> str:
    if isinstance(part, str):
        return part
    if isinstance(part, dict):
        for key in ("text", "content"):
            value = part.get(key)
            if isinstance(value, str):
                return value
        return json.dumps(part, ensure_ascii=False, sort_keys=True)
    return str(part)


def _format_timestamp(value: Any) -> Optional[str]:
    if value is None:
        return None
    if isinstance(value, (int, float)):
        dt = datetime.fromtimestamp(float(value), tz=timezone.utc)
    elif isinstance(value, datetime):
        dt = (value if value.tzinfo else value.replace(tzinfo=timezone.utc)).astimezone(timezone.utc)
    else:
        return str(value)
    return dt.isoformat(timespec="seconds").replace("+00:00", "Z")


def _session_metadata_lines(session: Dict[str, Any]) -> List[str]:
    lines: List[str] = [f"- Session ID: `{_session_id(session)}`"]
    for key, label in (("source", "Source"), ("model", "Model")):
        if session.get(key):
            lines.append(f"- {label}: `{session[key]}`")
    if title := session.get("title"):
        lines.append(f"- Title: {_inline_text(str(title))}")
    if started := _format_timestamp(session.get("started_at")):
        lines.append(f"- Started: {started}")
    if (message_count := session.get("message_count")) is not None:
        lines.append(f"- Messages: {message_count}")
    return lines


def _session_id(session: Dict[str, Any]) -> str:
    return str(session.get("id") or session.get("session_id") or "unknown")


def _session_title_or_id(session: Dict[str, Any]) -> str:
    return str(session.get("title") or "").strip() or _session_id(session)


def _heading_text(value: str) -> str:
    return " ".join(str(value).splitlines()).strip() or "unknown"


def _inline_text(value: str) -> str:
    return " ".join(value.splitlines()).strip()


def _fenced_text(text: str, *, language: str = "text") -> str:
    fence = "```"
    while fence in text:
        fence += "`"
    return f"{fence}{language}\n{text}\n{fence}"


def _finish_markdown(lines: List[str]) -> str:
    while lines and lines[-1] == "":
        lines.pop()
    return "\n".join(lines) + "\n"


# ---------------------------------------------------------------------------
# Current-session save helper (shared by CLI /save and gateway /save)
# ---------------------------------------------------------------------------

SAVE_FORMATS = ("json", "md", "html")

SAVE_USAGE = """/save — export the current session to a file
Usage: /save <format> [filename] [redact]

Formats:
  json    full session snapshot (canonical export shape)
  md      readable Markdown transcript
  html    standalone single-file HTML page (shareable, no dependencies)

Options:
  filename   optional output name/path (default: auto-named;
             CLI saves under ~/.hermes/sessions/saved/)
  redact     scrub API keys, tokens, and credentials before writing

Examples:
  /save json
  /save html
  /save md notes.md
  /save html session.html redact"""


def normalize_save_format(fmt: Optional[str]) -> str:
    """Map a user-typed /save format token to a canonical format."""
    token = (fmt or "json").strip().lower()
    canonical = {"json": "json", "snapshot": "json", "md": "md", "markdown": "md", "html": "html"}
    if token not in canonical:
        raise ValueError(
            f"Unknown format {token!r} — expected one of: json, md, html"
        )
    return canonical[token]


def render_session_for_save(session: Dict[str, Any], fmt: str) -> str:
    """Render one exported session dict for /save."""
    if fmt == "json":
        return json.dumps(session, indent=2, ensure_ascii=False, default=str)
    if fmt == "md":
        return render_sessions_export([session], fmt="markdown")
    if fmt == "html":
        from hermes_cli.session_export_html import generate_html_export

        return generate_html_export(session)
    raise ValueError(f"Unknown save format: {fmt!r}")


def default_save_filename(session_id: str, fmt: str) -> str:
    """Default filename for a /save export of the given session."""
    safe_id = "".join(
        ch for ch in str(session_id) if ch.isalnum() or ch in ("-", "_")
    ) or "session"
    return f"hermes_session_{safe_id}.{fmt}"