"""Claude Memory API — shared persistent memory with PostgreSQL full-text search."""

import os
from contextlib import asynccontextmanager
from datetime import datetime, timezone
from typing import Optional

import asyncpg
from fastapi import Depends, FastAPI, Header, HTTPException
from pydantic import BaseModel, Field

DATABASE_URL = os.environ["DATABASE_URL"]
API_KEY = os.environ["API_KEY"]

pool: asyncpg.Pool


@asynccontextmanager
async def lifespan(app: FastAPI):
    global pool
    pool = await asyncpg.create_pool(DATABASE_URL, min_size=2, max_size=10)
    async with pool.acquire() as conn:
        await conn.execute("""
            CREATE TABLE IF NOT EXISTS memories (
                id SERIAL PRIMARY KEY,
                content TEXT NOT NULL,
                category VARCHAR(50) DEFAULT 'facts',
                tags TEXT DEFAULT '',
                expanded_keywords TEXT DEFAULT '',
                importance REAL DEFAULT 0.5,
                created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
                updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
                search_vector tsvector GENERATED ALWAYS AS (
                    setweight(to_tsvector('english', coalesce(content, '')), 'A') ||
                    setweight(to_tsvector('english', coalesce(expanded_keywords, '')), 'B') ||
                    setweight(to_tsvector('english', coalesce(tags, '')), 'C') ||
                    setweight(to_tsvector('english', coalesce(category, '')), 'D')
                ) STORED
            )
        """)
        await conn.execute("""
            CREATE INDEX IF NOT EXISTS idx_memories_search
            ON memories USING GIN(search_vector)
        """)
    yield
    await pool.close()


app = FastAPI(title="Claude Memory API", lifespan=lifespan)


async def verify_api_key(authorization: str = Header(...)):
    if authorization != f"Bearer {API_KEY}":
        raise HTTPException(status_code=401, detail="Invalid API key")


class MemoryStore(BaseModel):
    content: str
    category: str = "facts"
    tags: str = ""
    expanded_keywords: str = ""
    importance: float = Field(default=0.5, ge=0.0, le=1.0)


class MemoryRecall(BaseModel):
    context: str
    expanded_query: str = ""
    category: Optional[str] = None
    sort_by: str = "importance"
    limit: int = 10


@app.get("/health")
async def health():
    async with pool.acquire() as conn:
        await conn.fetchval("SELECT 1")
    return {"status": "ok"}


@app.post("/api/memories", dependencies=[Depends(verify_api_key)])
async def store_memory(mem: MemoryStore):
    now = datetime.now(timezone.utc)
    async with pool.acquire() as conn:
        row = await conn.fetchrow(
            """INSERT INTO memories (content, category, tags, expanded_keywords, importance, created_at, updated_at)
               VALUES ($1, $2, $3, $4, $5, $6, $6)
               RETURNING id""",
            mem.content, mem.category, mem.tags, mem.expanded_keywords, mem.importance, now,
        )
    return {"id": row["id"], "category": mem.category, "importance": mem.importance}


@app.post("/api/memories/recall", dependencies=[Depends(verify_api_key)])
async def recall_memories(req: MemoryRecall):
    terms = f"{req.context} {req.expanded_query}".strip()
    words = [w for w in terms.split() if w]
    if not words:
        raise HTTPException(status_code=400, detail="context is required")

    if req.sort_by == "relevance":
        order = "ts_rank(m.search_vector, query) DESC, m.importance DESC"
    else:
        order = "m.importance DESC, m.created_at DESC"

    category_filter = "AND m.category = $3" if req.category else ""

    # Use websearch_to_tsquery which handles stop words and short tokens gracefully,
    # with OR between terms so any match surfaces results
    websearch_input = " OR ".join(words)

    sql = f"""
        SELECT m.id, m.content, m.category, m.tags, m.importance,
               m.created_at, ts_rank(m.search_vector, query) AS rank
        FROM memories m, websearch_to_tsquery('english', $1) query
        WHERE m.search_vector @@ query {category_filter}
        ORDER BY {order}
        LIMIT $2
    """

    async with pool.acquire() as conn:
        try:
            if req.category:
                rows = await conn.fetch(sql, websearch_input, req.limit, req.category)
            else:
                rows = await conn.fetch(sql, websearch_input, req.limit)
        except Exception:
            rows = []

    if not rows:
        # Fallback to ILIKE search for terms the stemmer can't handle
        like = f"%{req.context}%"
        sql_fallback = f"""
            SELECT id, content, category, tags, importance, created_at, 0.0 AS rank
            FROM memories
            WHERE (content ILIKE $1 OR tags ILIKE $1 OR expanded_keywords ILIKE $1)
            {("AND category = $3" if req.category else "")}
            ORDER BY importance DESC, created_at DESC
            LIMIT $2
        """
        async with pool.acquire() as conn:
            if req.category:
                rows = await conn.fetch(sql_fallback, like, req.limit, req.category)
            else:
                rows = await conn.fetch(sql_fallback, like, req.limit)

    return {"memories": [dict(r) for r in rows]}


@app.get("/api/memories", dependencies=[Depends(verify_api_key)])
async def list_memories(category: Optional[str] = None, limit: int = 20):
    async with pool.acquire() as conn:
        if category:
            rows = await conn.fetch(
                "SELECT id, content, category, tags, importance, created_at FROM memories WHERE category = $1 ORDER BY created_at DESC LIMIT $2",
                category, limit,
            )
        else:
            rows = await conn.fetch(
                "SELECT id, content, category, tags, importance, created_at FROM memories ORDER BY created_at DESC LIMIT $1",
                limit,
            )
    return {"memories": [dict(r) for r in rows]}


@app.delete("/api/memories/{memory_id}", dependencies=[Depends(verify_api_key)])
async def delete_memory(memory_id: int):
    async with pool.acquire() as conn:
        row = await conn.fetchrow("DELETE FROM memories WHERE id = $1 RETURNING id, substr(content, 1, 50) AS preview", memory_id)
    if not row:
        raise HTTPException(status_code=404, detail=f"Memory #{memory_id} not found")
    return {"deleted": row["id"], "preview": row["preview"]}


@app.post("/api/memories/import", dependencies=[Depends(verify_api_key)])
async def import_memories(memories: list[MemoryStore]):
    """Bulk import memories (for migrating from SQLite)."""
    now = datetime.now(timezone.utc)
    imported = 0
    async with pool.acquire() as conn:
        for mem in memories:
            await conn.execute(
                """INSERT INTO memories (content, category, tags, expanded_keywords, importance, created_at, updated_at)
                   VALUES ($1, $2, $3, $4, $5, $6, $6)""",
                mem.content, mem.category, mem.tags, mem.expanded_keywords, mem.importance, now,
            )
            imported += 1
    return {"imported": imported}