import json
from pathlib import Path

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel

from .. import database as db, config
from ..pipeline.turns import distinct_speakers, load_turns

router = APIRouter(prefix="/api/sessions/{session_id}/speakers", tags=["speakers"])


def _get_session_or_404(session_id: str):
    row = db.get_conn().execute("SELECT * FROM sessions WHERE id = ?", (session_id,)).fetchone()
    if not row:
        raise HTTPException(404, "Session not found")
    return dict(row)


@router.get("")
def get_speakers(session_id: str):
    session = _get_session_or_404(session_id)
    if not session["transcript_path"]:
        raise HTTPException(400, "Session hasn't been transcribed yet")

    speakers = distinct_speakers(Path(session["transcript_path"]))

    existing = {r["raw_label"]: r["display_name"] for r in
                db.get_conn().execute("SELECT raw_label, display_name FROM speakers WHERE session_id = ?", (session_id,))}

    for sp in speakers:
        sp["display_name"] = existing.get(sp["raw_label"], "")
    return speakers


class SpeakerName(BaseModel):
    raw_label: str
    display_name: str


@router.put("")
def set_speaker_name(session_id: str, body: SpeakerName):
    _get_session_or_404(session_id)
    with db.tx() as conn:
        conn.execute(
            "INSERT INTO speakers (id, session_id, raw_label, display_name) VALUES (?, ?, ?, ?) "
            "ON CONFLICT(session_id, raw_label) DO UPDATE SET display_name = excluded.display_name",
            (db.new_id(), session_id, body.raw_label, body.display_name),
        )
    return {"ok": True}


class MergeSpeakersBody(BaseModel):
    target_label: str
    source_labels: list[str]


@router.post("/merge")
def merge_speakers(session_id: str, body: MergeSpeakersBody):
    session = _get_session_or_404(session_id)
    if not session["transcript_path"]:
        raise HTTPException(400, "Session hasn't been transcribed yet")
    if body.target_label in body.source_labels:
        raise HTTPException(400, "Target label cannot also be a source label")

    tp = Path(session["transcript_path"])
    data = json.loads(tp.read_text())
    changed = 0
    for seg in data.get("segments", []):
        if seg.get("speaker") in body.source_labels:
            seg["speaker"] = body.target_label
            changed += 1
    tp.write_text(json.dumps(data, ensure_ascii=False), encoding="utf-8")

    with db.tx() as conn:
        for label in body.source_labels:
            conn.execute("DELETE FROM speakers WHERE session_id = ? AND raw_label = ?", (session_id, label))

    return {"ok": True, "segments_reassigned": changed}


@router.get("/turns")
def get_turns(session_id: str):
    """Full transcript with display names applied - powers the review/playback screen."""
    session = _get_session_or_404(session_id)
    if not session["transcript_path"]:
        raise HTTPException(400, "Session hasn't been transcribed yet")
    speaker_map = {r["raw_label"]: r["display_name"] for r in
                   db.get_conn().execute("SELECT raw_label, display_name FROM speakers WHERE session_id = ?", (session_id,))
                   if r["display_name"]}
    return load_turns(Path(session["transcript_path"]), speaker_map)