"""
IngestAgent — decodes video, normalizes FPS, samples frames.

Input:  video file path (str)
Output: IngestResult(frames, fps, duration, n_people, width, height)
Failure: returns IngestResult with confidence=0.0 and notes explaining the error.
Params: 0 (no model — pure OpenCV).
License: n/a.
Gated: no.
"""
from __future__ import annotations

import cv2
from pathlib import Path

from formscout.types import IngestResult
from formscout import config


class IngestAgent:
    """Deterministic video ingestion — no model, just OpenCV decode + frame sampling."""

    def run(self, video_path: str) -> IngestResult:
        p = Path(video_path)
        if not p.exists():
            return IngestResult(
                frames=[], fps=0.0, duration=0.0, n_people=0,
                width=0, height=0, confidence=0.0,
                notes=f"video not found: {video_path}",
            )

        try:
            cap = cv2.VideoCapture(str(p))
        except Exception as e:
            return IngestResult(
                frames=[], fps=0.0, duration=0.0, n_people=0,
                width=0, height=0, confidence=0.0,
                notes=f"failed to open video: {e}",
            )

        if not cap.isOpened():
            return IngestResult(
                frames=[], fps=0.0, duration=0.0, n_people=0,
                width=0, height=0, confidence=0.0,
                notes=f"could not open video: {video_path}",
            )

        fps = cap.get(cv2.CAP_PROP_FPS) or config.TARGET_FPS
        total = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
        w = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        h = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
        duration = total / fps if fps > 0 else 0.0

        notes_parts: list[str] = []
        if duration > config.MAX_DURATION_SEC:
            notes_parts.append(
                f"video is {duration:.1f}s (>{config.MAX_DURATION_SEC}s) — capping frames"
            )

        # Sample frames evenly, capped at MAX_FRAMES
        step = max(1, total // config.MAX_FRAMES)
        frames: list = []
        idx = 0
        while True:
            ret, frame = cap.read()
            if not ret:
                break
            if idx % step == 0:
                frames.append(frame)
            idx += 1
            if len(frames) >= config.MAX_FRAMES:
                break
        cap.release()

        if not frames:
            return IngestResult(
                frames=[], fps=fps, duration=duration, n_people=0,
                width=w, height=h, confidence=0.0,
                notes="no frames decoded",
            )

        return IngestResult(
            frames=frames,
            fps=fps,
            duration=duration,
            n_people=-1,  # unknown until segmentation/pose
            width=w,
            height=h,
            confidence=1.0,
            notes="; ".join(notes_parts) if notes_parts else "",
        )