"""
Inara tiered memory distillation.

  distill_short()  — roll recent session logs → MEMORY_SHORT.md  (no LLM)
  distill_mid()    — summarize MEMORY_SHORT   → MEMORY_MID.md    (LLM)
  distill_long()   — integrate MEMORY_MID     → MEMORY_LONG.md   (LLM)
"""
import logging
from datetime import datetime
from pathlib import Path
from config import settings
from persona import persona_path as _persona_path

logger = logging.getLogger(__name__)

# Rough chars-per-token estimate for budget enforcement
_CHARS_PER_TOKEN = 4


def _budget_chars(tokens: int) -> int:
    return tokens * _CHARS_PER_TOKEN


def _read(path: Path) -> str:
    return path.read_text() if path.exists() else ""


def distill_short(username: str | None = None, persona: str | None = None) -> dict:
    """
    Roll the most recent session log files into MEMORY_SHORT.md.
    No LLM involved — pure aggregation with budget truncation.
    Files are included newest-first until the budget is reached,
    then written in chronological order (oldest first).
    """
    inara_dir = _persona_path(username, persona)
    sessions_dir = inara_dir / "sessions"
    budget = _budget_chars(settings.memory_budget_short)

    session_files = (
        sorted(sessions_dir.glob("*.md"), reverse=True)
        if sessions_dir.exists()
        else []
    )

    parts = []
    total_chars = 0
    for sf in session_files:
        content = sf.read_text()
        if total_chars + len(content) > budget and parts:
            break  # always include at least one file
        parts.append((sf.name, content))
        total_chars += len(content)
        if total_chars >= budget:
            break

    now = datetime.now().strftime("%Y-%m-%d %H:%M")
    header = (
        f"# MEMORY_SHORT.md — Recent Session Digest\n\n"
        f"*Auto-generated: {now}. {len(parts)} session file(s).*\n\n---\n\n"
    )
    # Write in chronological order (oldest first)
    body = "\n\n".join(
        f"--- {name} ---\n{content}" for name, content in reversed(parts)
    )

    out_path = inara_dir / "MEMORY_SHORT.md"
    out_path.write_text(header + body)
    logger.info("distill_short: wrote %d chars from %d files", len(header) + len(body), len(parts))

    return {
        "files_included": len(parts),
        "chars_written": len(header) + len(body),
        "budget_chars": budget,
    }


async def distill_mid(username: str | None = None, persona: str | None = None) -> dict:
    """
    Ask the LLM to summarize MEMORY_SHORT.md → MEMORY_MID.md.
    Uses DISTILL_BACKEND_MID if set (e.g. "local"), otherwise primary_backend.
    """
    from llm_client import complete
    from persona import set_context

    u = username or settings.user_name.lower()
    p = persona or settings.agent_name.lower()
    set_context(u, p)

    inara_dir = _persona_path(u, p)
    short_content = _read(inara_dir / "MEMORY_SHORT.md")

    if not short_content.strip() or "Not yet populated" in short_content:
        return {"error": "MEMORY_SHORT.md is empty — run distill/short first"}

    backend_override = settings.distill_backend_mid or None
    budget_tokens = settings.memory_budget_mid
    system_prompt = (
        f"You are {settings.agent_name}'s memory distillation system. "
        "Summarize the following recent session logs into a concise mid-term memory digest. "
        f"Target length: under {budget_tokens} tokens. "
        "Focus on: recurring themes, important decisions made, ongoing projects, "
        f"{settings.user_name}'s current state and priorities, and anything that should persist into future sessions. "
        f"Write in first person as {settings.agent_name} (e.g. '{settings.user_name} and I worked on...'). "
        "Use markdown headings. Be specific and concrete — no filler."
    )

    response_text, backend = await complete(
        system_prompt=system_prompt,
        messages=[{"role": "user", "content": short_content}],
        model=backend_override,
    )

    now = datetime.now().strftime("%Y-%m-%d %H:%M")
    header = (
        f"# MEMORY_MID.md — Mid-Term Memory Digest\n\n"
        f"*Auto-distilled: {now} via {backend}.*\n\n---\n\n"
    )
    out_path = inara_dir / "MEMORY_MID.md"
    out_path.write_text(header + response_text)
    logger.info("distill_mid: wrote %d chars via %s", len(header) + len(response_text), backend)

    return {
        "username": u,
        "backend": backend,
        "chars_written": len(header) + len(response_text),
        "budget_tokens": budget_tokens,
    }


async def distill_long(username: str | None = None, persona: str | None = None) -> dict:
    """
    Ask the LLM to integrate MEMORY_MID.md into MEMORY_LONG.md.
    Uses DISTILL_BACKEND_LONG if set, otherwise primary_backend.
    """
    from llm_client import complete
    from persona import set_context

    u = username or settings.user_name.lower()
    p = persona or settings.agent_name.lower()
    set_context(u, p)

    inara_dir = _persona_path(u, p)
    long_content = _read(inara_dir / "MEMORY_LONG.md")
    mid_content = _read(inara_dir / "MEMORY_MID.md")

    if not mid_content.strip() or "Not yet populated" in mid_content:
        return {"error": "MEMORY_MID.md is empty — run distill/mid first"}

    backend_override = settings.distill_backend_long or None
    budget_tokens = settings.memory_budget_long
    system_prompt = (
        f"You are {settings.agent_name}'s long-term memory curator. "
        "You will receive the current long-term memory and a recent mid-term digest. "
        f"Integrate the new information into the long-term memory. Target: under {budget_tokens} tokens. "
        "Rules: preserve important historical facts; update or replace stale information; "
        "absorb recurring themes from the mid-term digest; remove things no longer relevant. "
        "Return ONLY the updated MEMORY_LONG.md content in markdown. No preamble or commentary."
    )

    user_content = (
        f"## Current MEMORY_LONG.md\n\n{long_content}\n\n"
        f"## Recent MEMORY_MID.md to integrate\n\n{mid_content}"
    )

    response_text, backend = await complete(
        system_prompt=system_prompt,
        messages=[{"role": "user", "content": user_content}],
        model=backend_override,
    )

    # Ensure the file has the right header if the LLM dropped it
    now = datetime.now().strftime("%Y-%m-%d %H:%M")
    if not response_text.lstrip().startswith("# MEMORY_LONG"):
        response_text = (
            f"# MEMORY_LONG.md — {settings.agent_name} Long-Term Memory\n\n"
            f"*Last distilled: {now} via {backend}.*\n\n---\n\n"
            + response_text
        )

    out_path = inara_dir / "MEMORY_LONG.md"
    out_path.write_text(response_text)
    logger.info("distill_long: wrote %d chars via %s", len(response_text), backend)

    return {
        "username": u,
        "backend": backend,
        "chars_written": len(response_text),
        "budget_tokens": budget_tokens,
    }