from __future__ import annotations

import math
import os
from pathlib import Path
from typing import Any


IMAGE_EXTENSIONS = {".jpg", ".jpeg", ".png", ".webp", ".bmp"}


def dataset_image_count(raw_path: object) -> int:
    path = Path(str(raw_path or "")).expanduser()
    if not path.is_dir():
        return 0
    try:
        return sum(
            1 for item in path.rglob("*")
            if item.is_file() and item.suffix.casefold() in IMAGE_EXTENSIONS
        )
    except OSError:
        return 0


def _available_vram_gb() -> float | None:
    try:
        import pynvml

        pynvml.nvmlInit()
        try:
            handle = pynvml.nvmlDeviceGetHandleByIndex(0)
            return pynvml.nvmlDeviceGetMemoryInfo(handle).total / (1024 ** 3)
        finally:
            pynvml.nvmlShutdown()
    except Exception:
        return None


def recommend_training_settings(
    trainer: str,
    image_count: int,
    resolution: int,
    *,
    vram_gb: float | None = None,
) -> dict[str, Any]:
    """Return an explainable, conservative starting recipe for manual review."""
    trainer = str(trainer).casefold()
    images = max(10, int(image_count))
    resolution = max(64, min(512, int(resolution)))
    vram = _available_vram_gb() if vram_gb is None else vram_gb
    cpu_workers = max(2, min(8, (os.cpu_count() or 4) // 2))

    if trainer == "lora":
        epochs = max(20, min(200, round(8_000 / images)))
        return {
            "epochs": epochs,
            "settings": {},
            "summary": (
                f"ORION chose {epochs} epochs from about {images:,} images. "
                "The connected LoRA trainer continues to own its detailed recipe."
            ),
        }

    exposure_target = 180_000 if trainer == "ddpm" else 120_000
    minimum_epochs = 25
    maximum_epochs = 600 if trainer == "ddpm" else 300
    epochs = max(minimum_epochs, min(maximum_epochs, round(exposure_target / images)))
    batch_by_resolution = {
        64: 16 if trainer == "ddpm" else 12,
        128: 12 if trainer == "ddpm" else 8,
        256: 4 if trainer == "ddpm" else 4,
        384: 2,
        512: 1,
    }
    nearest_resolution = min(batch_by_resolution, key=lambda size: abs(size - resolution))
    batch = batch_by_resolution[nearest_resolution]
    if vram is not None and vram < 8:
        batch = max(1, batch // 2)
    gradient_checkpointing = resolution >= 384 or (vram is not None and vram < 8)
    settings: dict[str, Any] = {
        "batch_size": batch,
        "learning_rate": 0.0001 if trainer == "ddpm" else 0.0002,
        "gradient_accumulation_steps": 1,
        "dataloader_num_workers": cpu_workers,
        "mixed_precision": "fp16",
        "save_every": max(5, min(25, max(1, epochs // 10))),
        "preview_steps": 50 if trainer == "ddpm" else 10,
        "preview_every": max(5, min(50, max(1, epochs // 10))),
        "training_intensity": 100,
        "gradient_checkpointing": gradient_checkpointing,
    }
    if trainer == "flow":
        settings["gradient_accumulation"] = settings["gradient_accumulation_steps"]
        settings["workers"] = settings["dataloader_num_workers"]
    memory_note = (
        f" using the detected {vram:.0f} GB GPU" if vram is not None
        else " without assuming a specific GPU"
    )
    return {
        "epochs": epochs,
        "settings": settings,
        "summary": (
            f"ORION chose about {epochs:,} epochs ({images * epochs:,} image exposures), "
            f"batch {batch} at {resolution}px{memory_note}. Review this starting recipe before training."
        ),
    }


def review_training_plan(plan: Any) -> dict[str, Any]:
    """Give a conservative, explainable review without changing user settings."""
    findings: list[dict[str, str]] = []
    training_steps = [step for step in plan.steps if step.tool_id.endswith("_trainer")]
    projected_counts = {
        str(Path(str(step.arguments.get("output_dir", ""))).expanduser()): int(
            step.arguments.get("image_count", 0) or 0
        )
        for step in plan.steps
        if step.tool_id in {"dataset_collector", "youtube_video_collector"}
        and step.arguments.get("output_dir")
    }
    total_steps = 0
    estimated_high_minutes = 0

    for step in training_steps:
        args = step.arguments
        dataset_key = str(Path(str(args.get("dataset_dir", ""))).expanduser())
        images = dataset_image_count(args.get("dataset_dir")) or projected_counts.get(dataset_key, 0)
        epochs = max(1, int(args.get("epochs", 1) or 1))
        batch = max(1, int(args.get("batch_size", 1) or 1))
        accumulation = max(
            1,
            int(args.get("gradient_accumulation_steps", args.get("gradient_accumulation", 1)) or 1),
        )
        resolution = max(64, int(args.get("resolution", 256) or 256))
        exposures = images * epochs if images else 0
        optimizer_steps = math.ceil(images / batch / accumulation) * epochs if images else 0
        total_steps += optimizer_steps

        # This remains deliberately broad: it is a planning guardrail, not a promise.
        if exposures:
            resolution_factor = (resolution / 256) ** 2
            estimated_high_minutes += max(1, math.ceil(exposures * resolution_factor / batch * 0.003))

        label = step.title or step.tool_id.replace("_", " ").title()
        if images >= 1_000 and epochs >= 300:
            suggested_epochs = max(25, min(150, round(180_000 / images)))
            findings.append({
                "level": "warning",
                "message": (
                    f"{label}: {images:,} images × {epochs:,} epochs requests "
                    f"{exposures:,} image exposures. This resembles a small-dataset preset. "
                    f"Review the intent; about {suggested_epochs} epochs is a safer initial test."
                ),
            })
        elif exposures >= 1_000_000:
            findings.append({
                "level": "warning",
                "message": f"{label}: the plan exceeds 1,000,000 image exposures; confirm this is intentional.",
            })
        if images >= 750 and "batch_size" in args and batch == 1 and resolution <= 256:
            findings.append({
                "level": "warning",
                "message": (
                    f"{label}: batch size 1 at {resolution}px may leave substantial GPU capacity unused. "
                    "Try a short test with a larger batch if VRAM allows."
                ),
            })
        if epochs >= 1_000:
            findings.append({
                "level": "warning",
                "message": f"{label}: {epochs:,} epochs is unusually long and deserves explicit review.",
            })

    if not training_steps:
        return {}
    if not findings:
        findings.append({
            "level": "ready",
            "message": "No obviously accidental training settings were found. Estimates are still approximate.",
        })
    level = "warning" if any(item["level"] == "warning" for item in findings) else "ready"
    return {
        "agent": "ORION",
        "level": level,
        "headline": "Review recommended" if level == "warning" else "Plan looks reasonable",
        "findings": findings,
        "estimated_optimizer_steps": total_steps,
        "estimated_high_minutes": estimated_high_minutes,
        "settings_changed": False,
    }


def apply_orion_review(plan: Any) -> dict[str, Any]:
    review = review_training_plan(plan)
    plan.orion_review = review
    if not review:
        return review
    lines = [f"ORION — {review['headline']}"]
    lines.extend(f"• {item['message']}" for item in review["findings"])
    if review["estimated_optimizer_steps"]:
        lines.append(f"• Estimated optimizer steps: about {review['estimated_optimizer_steps']:,}")
    plan.summary += "\n\n" + "\n".join(lines)
    if review["level"] == "warning":
        plan.requires_confirmation = True
        reason = "ORION found unusual training settings. Review his findings before starting."
        if reason not in plan.confirmation_reason:
            plan.confirmation_reason = "; ".join(filter(None, [plan.confirmation_reason, reason]))
    return review