# windowing_utils.py
from __future__ import annotations
from dataclasses import dataclass, field
from typing import List, Dict, Callable, Optional, Tuple, Awaitable
import hashlib
import os
import time

# ---------- Token counting (vervang door echte tokenizer indien je wilt)
def approx_token_count(text: str) -> int:
    # ~4 chars ≈ 1 token (ruwe maar stabiele vuistregel)
    return max(1, len(text) // 4)

def count_message_tokens(messages: List[Dict], tok_len: Callable[[str], int]) -> int:
    total = 0
    for m in messages:
        total += tok_len(m.get("content", ""))
    return total

# ---------- Thread ID + summary store
def derive_thread_id(body: Dict) -> str:
    for key in ("conversation_id", "thread_id", "chat_id", "session_id", "room_id"):
        if key in body and body[key]:
            return str(body[key])
    parts = [str(body.get("model", ""))]
    msgs = body.get("messages", [])[:2]
    for m in msgs:
        parts.append(m.get("role", ""))
        parts.append(m.get("content", "")[:256])
    raw = "||".join(parts)
    return hashlib.sha256(raw.encode("utf-8")).hexdigest()[:16]

class RunningSummaryStore:
    def __init__(self):
        self._mem: dict[str, str] = {}
    def get(self, thread_id: str) -> str:
        return self._mem.get(thread_id, "")
    def update(self, thread_id: str, new_summary: str):
        self._mem[thread_id] = new_summary

SUMMARY_STORE = RunningSummaryStore()

# ---------- Sliding window + running summary
@dataclass
class ConversationWindow:
    max_ctx_tokens: int
    response_reserve: int = 2048
    tok_len: Callable[[str], int] = approx_token_count
    running_summary: str = ""
    summary_header: str = "Samenvatting tot nu toe"
    history: List[Dict] = field(default_factory=list)

    def add(self, role: str, content: str):
        self.history.append({"role": role, "content": content})

    def _base_messages(self, system_prompt: Optional[str]) -> List[Dict]:
        msgs: List[Dict] = []
        if system_prompt:
            msgs.append({"role": "system", "content": system_prompt})
        if self.running_summary:
            msgs.append({"role": "system", "content": f"{self.summary_header}:\n{self.running_summary}"})
        return msgs

    async def build_within_budget(
        self,
        system_prompt: Optional[str],
        summarizer: Optional[Callable[[str, List[Dict]], Awaitable[str]]] = None
    ) -> List[Dict]:
        budget = self.max_ctx_tokens - max(1, self.response_reserve)
        working = self.history[:]
        candidate = self._base_messages(system_prompt) + working
        if count_message_tokens(candidate, self.tok_len) <= budget:
            return candidate

        # 1) trim oudste turns
        while working and count_message_tokens(self._base_messages(system_prompt) + working, self.tok_len) > budget:
            working.pop(0)
        candidate = self._base_messages(system_prompt) + working
        if count_message_tokens(candidate, self.tok_len) <= budget:
            self.history = working
            return candidate

        # 2) samenvatten indien mogelijk
        if summarizer is None:
            while working and count_message_tokens(self._base_messages(system_prompt) + working, self.tok_len) > budget:
                working.pop(0)
            self.history = working
            return self._base_messages(system_prompt) + working

        # samenvat in batches
        working = self.history[:]
        chunk_buf: List[Dict] = []

        async def build_candidate(_summary: str, _working: List[Dict]) -> List[Dict]:
            base = []
            if system_prompt:
                base.append({"role": "system", "content": system_prompt})
            if _summary:
                base.append({"role": "system", "content": f"{self.summary_header}:\n{_summary}"})
            return base + _working

        while working and count_message_tokens(await build_candidate(self.running_summary, working), self.tok_len) > budget:
            chunk_buf.append(working.pop(0))
            # bij ~1500 tokens in buffer (ruw) samenvatten
            if count_message_tokens([{"role":"system","content":str(chunk_buf)}], self.tok_len) > 1500 or not working:
                self.running_summary = await summarizer(self.running_summary, chunk_buf)
                chunk_buf = []

        # verwerk eventuele overgebleven buffer zodat er geen turns verdwijnen
        if chunk_buf:
            self.running_summary = await summarizer(self.running_summary, chunk_buf)
            chunk_buf = []

        self.history = working
        return await build_candidate(self.running_summary, working)

# ---------- Repo chunking
from typing import Iterable
def split_text_tokens(
    text: str,
    tok_len: Callable[[str], int],
    max_tokens: int,
    overlap_tokens: int = 60
) -> List[str]:
    if tok_len(text) <= max_tokens:
        return [text]
    approx_ratio = max_tokens / max(1, tok_len(text))
    step = max(1000, int(len(text) * approx_ratio))
    chunks: List[str] = []
    i = 0
    while i < len(text):
        ch = text[i:i+step]
        while tok_len(ch) > max_tokens and len(ch) > 200:
            ch = ch[:-200]
        chunks.append(ch)
        if overlap_tokens > 0:
            ov_chars = max(100, overlap_tokens * 4)
            i += max(1, len(ch) - ov_chars)
        else:
            i += len(ch)
    return chunks

def fit_context_under_budget(
    items: List[Tuple[str,str]], tok_len: Callable[[str], int], budget_tokens: int
) -> List[Tuple[str,str]]:
    res: List[Tuple[str,str]] = []
    used = 0
    for title, text in items:
        t = tok_len(text)
        if used + t <= budget_tokens:
            res.append((title, text))
            used += t
        else:
            break
    return res

def build_repo_context(
    files_ranked: List[Tuple[str, str, float]],
    per_chunk_tokens: int = 1200,
    overlap_tokens: int = 60,
    ctx_budget_tokens: int = 4000,
    tok_len: Callable[[str], int] = approx_token_count
) -> str:
    expanded: List[Tuple[str,str]] = []
    for path, content, _ in files_ranked:
        for i, ch in enumerate(split_text_tokens(content, tok_len, per_chunk_tokens, overlap_tokens)):
            expanded.append((f"{path}#chunk{i+1}", ch))
    selected = fit_context_under_budget(expanded, tok_len, ctx_budget_tokens)
    ctx = ""
    for title, ch in selected:
        ctx += f"\n\n=== {title} ===\n{ch}"
    return ctx.strip()