from datetime import datetime, timedelta
from typing import Dict, List, Optional

from app.models import InferenceJob, JobResult, JobStatus, JobType, WorkerState, PrivacyMode
from app.security import generate_job_id
from app.storage import save_job_event
from app.session_store import list_workers, get_session

_jobs_by_id: Dict[str, InferenceJob] = {}


def create_job(session_id: str, job_type: JobType, payload: dict, privacy_mode: PrivacyMode, constraints: dict) -> InferenceJob:
    job = InferenceJob(
        job_id=generate_job_id(),
        session_id=session_id,
        job_type=job_type,
        privacy_mode=privacy_mode,
        payload=payload,
        constraints=constraints,
    )
    _jobs_by_id[job.job_id] = job
    save_job_event({
        "event": "created",
        "job_id": job.job_id,
        "session_id": session_id,
        "job_type": job_type.value,
        "timestamp": datetime.utcnow().isoformat(),
    })
    return job


def enqueue_job(job: InferenceJob) -> None:
    # v1: immediate assignment attempt; v2 can use real queue
    pass


def select_worker_for_job(session_id: str, job: InferenceJob) -> Optional[str]:
    workers = list_workers(session_id)
    if not workers:
        return None
    best = None
    best_score = -1.0
    for w in workers:
        score = _score_worker_for_job(w, job)
        if score > best_score:
            best_score = score
            best = w.worker_id
    return best


def _score_worker_for_job(worker: WorkerState, job: InferenceJob) -> float:
    score = 0.0
    # Capability match
    for cap in worker.capabilities:
        if cap.capability_name == job.job_type.value:
            score += 100.0
            break
    # Battery
    if worker.battery_level is not None and worker.battery_level > 0.2:
        score += 20.0
    # Thermal
    if worker.thermal_state in (None, "nominal", "fair"):
        score += 20.0
    # Heartbeat freshness
    age = (datetime.utcnow() - worker.last_heartbeat).total_seconds()
    if age < 10:
        score += 30.0
    elif age < 30:
        score += 10.0
    return score


def assign_job_to_worker(job_id: str, worker_id: str) -> bool:
    job = _jobs_by_id.get(job_id)
    if not job:
        return False
    job.worker_id = worker_id
    job.status = JobStatus.ASSIGNED
    job.assigned_at = datetime.utcnow()
    save_job_event({
        "event": "assigned",
        "job_id": job_id,
        "worker_id": worker_id,
        "timestamp": datetime.utcnow().isoformat(),
    })
    return True


def mark_job_running(job_id: str) -> bool:
    job = _jobs_by_id.get(job_id)
    if job:
        job.status = JobStatus.RUNNING
        return True
    return False


def complete_job(job_id: str, result: JobResult) -> bool:
    job = _jobs_by_id.get(job_id)
    if not job:
        return False
    job.status = JobStatus.COMPLETED
    job.result = result.output
    job.completed_at = datetime.utcnow()
    save_job_event({
        "event": "completed",
        "job_id": job_id,
        "worker_id": result.worker_id,
        "latency_ms": result.latency_ms,
        "timestamp": datetime.utcnow().isoformat(),
    })
    return True


def fail_job(job_id: str, reason: str) -> bool:
    job = _jobs_by_id.get(job_id)
    if job:
        job.status = JobStatus.FAILED
        job.error_reason = reason
        job.completed_at = datetime.utcnow()
        save_job_event({
            "event": "failed",
            "job_id": job_id,
            "reason": reason,
            "timestamp": datetime.utcnow().isoformat(),
        })
        return True
    return False


def reject_job(job_id: str, reason: str) -> bool:
    job = _jobs_by_id.get(job_id)
    if job:
        job.status = JobStatus.REJECTED
        job.error_reason = reason
        job.completed_at = datetime.utcnow()
        return True
    return False


def expire_old_jobs() -> None:
    from app.config import Settings
    ttl = Settings.get_job_ttl_seconds()
    now = datetime.utcnow()
    expired = []
    for jid, job in _jobs_by_id.items():
        if job.created_at + timedelta(seconds=ttl) < now and job.status in (JobStatus.QUEUED, JobStatus.ASSIGNED):
            expired.append(jid)
    for jid in expired:
        fail_job(jid, "expired")


def get_job(job_id: str) -> Optional[InferenceJob]:
    expire_old_jobs()
    return _jobs_by_id.get(job_id)


def list_jobs_for_session(session_id: str) -> List[InferenceJob]:
    expire_old_jobs()
    return [j for j in _jobs_by_id.values() if j.session_id == session_id]