from pathlib import Path
import hashlib
import hmac
import json
import os
import re
import sqlite3
import subprocess
import sys
import time
import unicodedata
from collections import Counter

from fastapi import FastAPI, Header, HTTPException, Request
from pydantic import BaseModel, Field


DB_FILE = Path("data/zp_index.sqlite")
ZPWIKI_ROOT = Path(os.getenv("ZPWIKI_ROOT", "../zpwiki"))
WEBHOOK_SECRET = os.getenv("WEBHOOK_SECRET", "dev-secret")


TECHNICAL_TERMS = {
    "rag",
    "agent",
    "graph",
    "knowledge",
    "chatbot",
    "nlp",
    "llm",
    "lm",
    "openwebui",
    "docker",
    "webhook",
    "database",
    "db",
    "neo4j",
    "python",
    "search",
    "retrieval",
    "generation",
    "embedding",
    "vector",
    "vectors",
    "langchain",
    "graphrag",
    "qa",
    "question",
    "answer",
    "cloud",
    "api",
}


app = FastAPI(
    title="ZP Agent API",
    description="API pre vyhľadávanie v repozitári záverečných prác zpwiki.",
    version="0.3.0",
)


class SearchRequest(BaseModel):
    query: str = Field(..., min_length=1)
    limit: int = Field(default=10, ge=1, le=50)


class SyncRequest(BaseModel):
    pull_git: bool = Field(
        default=False,
        description="Ak je true, pred reindexovaním sa vykoná git pull v repozitári zpwiki.",
    )


def normalize_text(text: str) -> str:
    text = text.lower()
    text = text.replace("_", " ")
    text = text.replace("/", " ")
    text = text.replace("-", " ")

    text = unicodedata.normalize("NFKD", text)
    text = "".join(ch for ch in text if not unicodedata.combining(ch))

    text = re.sub(r"[^a-z0-9]+", " ", text)
    return text.strip()


def tokenize(text: str) -> list[str]:
    text = normalize_text(text)
    return [word for word in text.split() if len(word) >= 2]


def detect_search_mode(query_tokens: list[str]) -> str:
    if not query_tokens:
        return "topic"

    has_technical_term = any(token in TECHNICAL_TERMS for token in query_tokens)

    if len(query_tokens) == 2 and not has_technical_term:
        return "person"

    return "topic"


def score_tokens(query_tokens: list[str], field_tokens: list[str], weight: int) -> int:
    counts = Counter(field_tokens)
    score = 0

    for token in query_tokens:
        score += counts.get(token, 0) * weight

    return score


def contains_all_tokens(query_tokens: list[str], field_tokens: list[str]) -> bool:
    return all(token in field_tokens for token in query_tokens)


def get_tags(conn: sqlite3.Connection, chunk_id: str) -> list[str]:
    rows = conn.execute(
        "SELECT tag FROM chunk_tags WHERE chunk_id = ?",
        (chunk_id,),
    ).fetchall()

    return [row[0] for row in rows]


def get_categories(conn: sqlite3.Connection, chunk_id: str) -> list[str]:
    rows = conn.execute(
        "SELECT category FROM chunk_categories WHERE chunk_id = ?",
        (chunk_id,),
    ).fetchall()

    return [row[0] for row in rows]


def person_match(query_tokens: list[str], item: dict) -> bool:
    title_tokens = tokenize(item.get("title") or "")
    path_tokens = tokenize(item.get("document_path") or "")
    author_tokens = tokenize(item.get("author") or "")
    text_tokens = tokenize(item.get("text") or "")

    if contains_all_tokens(query_tokens, title_tokens):
        return True

    if contains_all_tokens(query_tokens, path_tokens):
        return True

    if contains_all_tokens(query_tokens, author_tokens):
        return True

    if contains_all_tokens(query_tokens, text_tokens):
        return True

    return False


def score_item(query: str, query_tokens: list[str], item: dict, mode: str) -> int:
    title = item.get("title") or ""
    path = item.get("document_path") or ""
    author = item.get("author") or ""
    text = item.get("text") or ""
    tags = item.get("tags") or []
    categories = item.get("categories") or []

    title_tokens = tokenize(title)
    path_tokens = tokenize(path)
    author_tokens = tokenize(author)
    text_tokens = tokenize(text)
    tag_tokens = tokenize(" ".join(tags))
    category_tokens = tokenize(" ".join(categories))

    score = 0

    if mode == "person":
        score += score_tokens(query_tokens, title_tokens, 30)
        score += score_tokens(query_tokens, path_tokens, 30)
        score += score_tokens(query_tokens, author_tokens, 15)
        score += score_tokens(query_tokens, text_tokens, 2)

        if contains_all_tokens(query_tokens, title_tokens):
            score += 100

        if contains_all_tokens(query_tokens, path_tokens):
            score += 100

        if contains_all_tokens(query_tokens, author_tokens):
            score += 60

        return score

    score += score_tokens(query_tokens, title_tokens, 12)
    score += score_tokens(query_tokens, path_tokens, 12)
    score += score_tokens(query_tokens, tag_tokens, 10)
    score += score_tokens(query_tokens, category_tokens, 6)
    score += score_tokens(query_tokens, author_tokens, 3)
    score += score_tokens(query_tokens, text_tokens, 2)

    normalized_query = normalize_text(query)
    normalized_title = normalize_text(title)
    normalized_path = normalize_text(path)

    if normalized_query and normalized_query in normalized_title:
        score += 30

    if normalized_query and normalized_query in normalized_path:
        score += 30

    matched_title_tokens = sum(1 for token in query_tokens if token in title_tokens)
    matched_path_tokens = sum(1 for token in query_tokens if token in path_tokens)

    if query_tokens and matched_title_tokens == len(query_tokens):
        score += 25

    if query_tokens and matched_path_tokens == len(query_tokens):
        score += 25

    return score


def make_source_url(document_path: str) -> str:
    clean_path = document_path.replace("pages/", "").replace("/README.md", "")
    return f"https://zp.kemt.fei.tuke.sk/{clean_path}"


def search_database(query: str, limit: int) -> tuple[str, list[dict]]:
    if not DB_FILE.exists():
        raise FileNotFoundError(f"Databáza neexistuje: {DB_FILE}")

    query_tokens = tokenize(query)
    mode = detect_search_mode(query_tokens)

    conn = sqlite3.connect(DB_FILE)

    rows = conn.execute("""
        SELECT chunk_id, document_path, title, author, chunk_index, text, text_length
        FROM chunks
    """).fetchall()

    results = []

    for row in rows:
        chunk_id, document_path, title, author, chunk_index, text, text_length = row

        item = {
            "chunk_id": chunk_id,
            "document_path": document_path,
            "title": title,
            "author": author,
            "chunk_index": chunk_index,
            "text": text,
            "text_length": text_length,
            "tags": get_tags(conn, chunk_id),
            "categories": get_categories(conn, chunk_id),
        }

        if mode == "person" and not person_match(query_tokens, item):
            continue

        score = score_item(query, query_tokens, item, mode)

        if score > 0:
            item["score"] = score
            item["source_url"] = make_source_url(document_path)
            results.append(item)

    conn.close()

    results.sort(key=lambda item: item["score"], reverse=True)

    return mode, results[:limit]


def run_command(command: list[str], cwd: Path | None = None) -> str:
    result = subprocess.run(
        command,
        cwd=cwd,
        text=True,
        capture_output=True,
    )

    output = ""

    if result.stdout:
        output += result.stdout

    if result.stderr:
        output += result.stderr

    if result.returncode != 0:
        raise RuntimeError(output.strip())

    return output.strip()


def get_index_counts() -> dict:
    if not DB_FILE.exists():
        return {
            "documents": 0,
            "chunks": 0,
            "tags": 0,
            "categories": 0,
        }

    conn = sqlite3.connect(DB_FILE)
    cursor = conn.cursor()

    counts = {
        "documents": cursor.execute("SELECT COUNT(*) FROM documents").fetchone()[0],
        "chunks": cursor.execute("SELECT COUNT(*) FROM chunks").fetchone()[0],
        "tags": cursor.execute("SELECT COUNT(*) FROM chunk_tags").fetchone()[0],
        "categories": cursor.execute("SELECT COUNT(*) FROM chunk_categories").fetchone()[0],
    }

    conn.close()
    return counts


def rebuild_index(pull_git: bool = False) -> dict:
    start = time.time()
    logs = []

    if pull_git:
        if not ZPWIKI_ROOT.exists():
            raise RuntimeError(f"ZPWIKI_ROOT neexistuje: {ZPWIKI_ROOT}")

        if not (ZPWIKI_ROOT / ".git").exists():
            raise RuntimeError(f"Nie je to git repozitár: {ZPWIKI_ROOT}")

        logs.append(run_command(["git", "pull"], cwd=ZPWIKI_ROOT))

    logs.append(run_command([sys.executable, "scripts/scan_zpwiki.py"]))
    logs.append(run_command([sys.executable, "scripts/build_chunks.py"]))
    logs.append(run_command([sys.executable, "scripts/build_sqlite_index.py"]))

    counts = get_index_counts()
    duration = round(time.time() - start, 2)

    return {
        "duration_seconds": duration,
        "counts": counts,
        "logs": logs,
    }


def verify_gitea_signature(raw_body: bytes, signature: str | None) -> bool:
    if not signature:
        return False

    expected = hmac.new(
        WEBHOOK_SECRET.encode("utf-8"),
        raw_body,
        hashlib.sha256,
    ).hexdigest()

    signature = signature.strip()

    if signature.startswith("sha256="):
        signature = signature.replace("sha256=", "", 1)

    return hmac.compare_digest(expected, signature)


def verify_simple_token(token: str | None) -> bool:
    if not token:
        return False

    return hmac.compare_digest(token, WEBHOOK_SECRET)


@app.get("/health")
def health():
    return {
        "status": "ok",
        "database_exists": DB_FILE.exists(),
        "database_path": str(DB_FILE),
        "zpwiki_root": str(ZPWIKI_ROOT),
        "zpwiki_exists": ZPWIKI_ROOT.exists(),
        "webhook_secret_configured": bool(WEBHOOK_SECRET),
    }


@app.post("/search")
def search(request: SearchRequest):
    try:
        mode, results = search_database(request.query, request.limit)
    except FileNotFoundError as error:
        raise HTTPException(status_code=500, detail=str(error)) from error

    return {
        "query": request.query,
        "mode": mode,
        "count": len(results),
        "results": results,
    }


@app.post("/sync")
def sync(request: SyncRequest):
    try:
        result = rebuild_index(pull_git=request.pull_git)
    except RuntimeError as error:
        raise HTTPException(status_code=500, detail=str(error)) from error

    return {
        "status": "ok",
        "pull_git": request.pull_git,
        "duration_seconds": result["duration_seconds"],
        "counts": result["counts"],
    }


@app.post("/webhook/gitea")
async def gitea_webhook(
    request: Request,
    x_gitea_event: str | None = Header(default=None, alias="X-Gitea-Event"),
    x_gitea_signature: str | None = Header(default=None, alias="X-Gitea-Signature"),
    x_gitea_token: str | None = Header(default=None, alias="X-Gitea-Token"),
):
    raw_body = await request.body()

    signature_ok = verify_gitea_signature(raw_body, x_gitea_signature)
    token_ok = verify_simple_token(x_gitea_token)

    if not signature_ok and not token_ok:
        raise HTTPException(
            status_code=401,
            detail="Invalid webhook signature or token",
        )

    try:
        payload = json.loads(raw_body.decode("utf-8")) if raw_body else {}
    except json.JSONDecodeError:
        payload = {}

    repository = payload.get("repository", {})
    repository_name = repository.get("full_name") or repository.get("name")

    try:
        result = rebuild_index(pull_git=False)
    except RuntimeError as error:
        raise HTTPException(status_code=500, detail=str(error)) from error

    return {
        "status": "ok",
        "event": x_gitea_event or "unknown",
        "repository": repository_name,
        "verified_by": "signature" if signature_ok else "token",
        "duration_seconds": result["duration_seconds"],
        "counts": result["counts"],
    }