"""
Material Library API
Scans huggingfaceapi/material_api/Materials/ (structured like the CityEngine lib)
and serves .cgamat metadata + texture files.

Run: .venv/Scripts/python.exe -m uvicorn huggingfaceapi.material_api.main:app --port 8001 --reload
"""
from __future__ import annotations  # enables str|None, dict[...], list[...] on Python 3.9
import os
from pathlib import Path
from typing import Any, Dict, Optional, Tuple
from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse


# ── Config ─────────────────────────────────────────────────────────────────

# Materials directory sits alongside this script, just like the rpk/ folder in app.py
MATERIALS_ROOT = Path(os.path.join(os.path.dirname(__file__), "Materials"))

# Ensure it exists (create on first run)
MATERIALS_ROOT.mkdir(parents=True, exist_ok=True)

# ── Known structure (authoritative folder tree) ──────────────────────────────
# Drop your .cgamat + Textures/ folders into these leaf directories.
KNOWN_STRUCTURE: dict[str, dict[str, list[str]]] = {
    "Architectural": {
        "Cladding": ["Aluminium", "Ceramic", "Corrugated", "Corten", "FiberCement", "Terracotta", "Travertine", "Wood"],
        "Exterior":  ["Pebbles"],
        "Misc":      ["SolarPanels"],
        "Roofing":   ["Concrete", "Slate", "Terracotta"],
        "Walls":     ["Brick", "Concrete", "Plaster"],
    },
    "Generic": {
        "":       ["Asphalt", "Glass", "Slate", "Terracotta", "Test_Patterns", "Wood"],
        "Metal":  ["Aluminum", "Steel"],
        "Plastic": ["PVC"],
    },
    "Street": {
        "Road":     ["Asphalt", "Markings"],
        "Sidewalk": ["Concrete", "Paver"],
    },
    "Vegetation": {
        "": ["Grass", "Soil"],
    },
}

def _ensure_known_dirs() -> None:
    """Create all leaf directories from KNOWN_STRUCTURE so users can just drop files in."""
    for cat, subs in KNOWN_STRUCTURE.items():
        for sub, groups in subs.items():
            for grp in groups:
                leaf = MATERIALS_ROOT / cat / sub / grp if sub else MATERIALS_ROOT / cat / grp
                leaf.mkdir(parents=True, exist_ok=True)

_ensure_known_dirs()

app = FastAPI(title="Material Library API")

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_methods=["*"],
    allow_headers=["*"],
)

# ── .cgamat parser ───────────────────────────────────────────────────────────

def parse_cgamat(filepath: Path) -> dict[str, Any]:
    """Parse a CityEngine .cgamat key,value file into a PBR descriptor dict."""
    props: dict[str, str] = {}
    try:
        for line in filepath.read_text(encoding="utf-8", errors="ignore").splitlines():
            line = line.strip()
            if not line or line.startswith("#"):
                continue
            parts = line.split(",", 1)
            if len(parts) == 2:
                props[parts[0].strip()] = parts[1].strip()
    except Exception:
        pass

    # Textures are relative to the .cgamat file's parent directory
    base_dir = filepath.parent

    def tex_url(key: str) -> Optional[str]:
        """
        Resolve a texture path from a .cgamat property to a /texture/... URL.

        Handles two issues:
        1. .tif/.tiff files — browsers cannot decode TIFF natively, so we look
           for a .jpg/.png/.webp sibling with the same stem before giving up.
        2. Missing files — quietly returns None so the material still renders
           with its base colour.
        """
        raw = props.get(key, "").strip()
        if not raw:
            return None
        abs_path = (base_dir / raw).resolve()

        # .tif/.tiff → try browser-compatible alternatives
        if abs_path.suffix.lower() in (".tif", ".tiff"):
            for alt_ext in (".jpg", ".jpeg", ".png", ".webp"):
                alt = abs_path.with_suffix(alt_ext)
                if alt.exists():
                    abs_path = alt
                    break
            else:
                # no browser-friendly alternative found
                return None

        if not abs_path.exists():
            return None
        try:
            rel = abs_path.relative_to(MATERIALS_ROOT)
            return "/texture/" + rel.as_posix()
        except ValueError:
            return None

    # Tiling: use colormap scale factors as primary, fall back to roughnessmap's
    tiling_u = float(props.get("colormap.su") or props.get("roughnessmap.su") or 1)
    tiling_v = float(props.get("colormap.sv") or props.get("roughnessmap.sv") or 1)

    # opacitymap.mode: "blend" = transparent (glass), "opaque" = solid
    opacity_mode = props.get("opacitymap.mode", "opaque").strip().lower()

    return {
        "name":            props.get("name", filepath.stem),
        "color":           [
            float(props.get("color.r", 1)),
            float(props.get("color.g", 1)),
            float(props.get("color.b", 1)),
        ],
        "roughness":       float(props.get("roughness", 0.8)),
        "metalness":       float(props.get("metallic", 0.0)),
        "opacity":         float(props.get("opacity", 1.0)),
        # opaque = solid surface; blend = alpha-transparent (glass, foliage, etc.)
        "opacityMode":     opacity_mode,
        "colormap":        tex_url("colormap"),
        "normalmap":       tex_url("normalmap"),
        # Combined MetallicRoughness texture: G-channel = roughness, B-channel = metalness
        "roughnessmap":    tex_url("roughnessmap"),
        # Separate metallic-only map (rare; most materials use roughnessmap B-channel)
        "metallicmap":     tex_url("metallicmap"),
        "tilingU":         tiling_u,
        "tilingV":         tiling_v,
    }

# ── Preview lookup ───────────────────────────────────────────────────────────

def find_preview(cgamat: Path) -> Optional[str]:
    """
    Look for a preview image for this .cgamat in:
      <cgamat_folder>/Textures/.prvw/<stem>*.(jpg|png)

    The .prvw folder contains thumbnail images named after the cgamat stem,
    e.g.  CorrugatedPanels_Borga_1x3_cAgateGrey_Color.jpg
    or    CorrugatedPanels_Borga_1x3_cAgateGrey_Color.jpg.jpg  (double-ext variant)
    """
    stem = cgamat.stem.lower()
    prvw_dir = cgamat.parent / "Textures" / ".prvw"
    if not prvw_dir.is_dir():
        return None

    best: Optional[Path] = None
    for img in prvw_dir.iterdir():
        name_lower = img.name.lower()
        # Match on stem presence; prefer files without double extension
        if stem in name_lower and img.suffix.lower() in (".jpg", ".jpeg", ".png", ".webp"):
            # Prefer non-double-extension files
            if best is None or (not name_lower.endswith(".jpg.jpg") and best.name.lower().endswith(".jpg.jpg")):
                best = img

    if best is not None:
        try:
            rel = best.relative_to(MATERIALS_ROOT)
            return "/texture/" + rel.as_posix()
        except ValueError:
            pass
    return None

# ── Directory structure mapping ──────────────────────────────────────────────
#
# Actual folder layout (variable depth):
#
#   Materials/
#     <category>/
#       [<subcategory>/]        ← 0 or more intermediate folders
#         <group>/              ← leaf folder containing .cgamat files
#           File.cgamat
#           Textures/
#             .prvw/
#
# Examples:
#   Generic/Asphalt/Asphalt_1x1.cgamat
#     → parts = ('Generic', 'Asphalt', 'Asphalt_1x1.cgamat')
#     → category='Generic'  subcategory=''       group='Asphalt'
#
#   Architectural/Cladding/Corrugated/File.cgamat
#     → parts = ('Architectural', 'Cladding', 'Corrugated', 'File.cgamat')
#     → category='Architectural'  subcategory='Cladding'  group='Corrugated'
#
#   Street/Road/Asphalt/File.cgamat
#     → parts = ('Street', 'Road', 'Asphalt', 'File.cgamat')
#     → category='Street'  subcategory='Road'  group='Asphalt'
#
# Rule:
#   parts[0]    = category
#   parts[-2]   = group  (the leaf folder)
#   parts[1:-2] = subcategory intermediate parts

def _classify(rel: Path) -> Tuple[str, str, str]:
    """Return (category, subcategory, group) from a relative cgamat path."""
    parts = rel.parts          # includes the filename as last element
    if len(parts) < 2:
        return ("Other", "", "")
    category    = parts[0]
    group       = parts[-2]    # leaf folder
    subcategory = "/".join(parts[1:-2])  # empty string if only 1 intermediate level
    return (category, subcategory, group)

# ── Build material index at startup ─────────────────────────────────────────

def scan_materials() -> list[dict]:
    results = []
    if not MATERIALS_ROOT.exists():
        return results

    for cgamat in sorted(MATERIALS_ROOT.rglob("*.cgamat")):
        # Skip anything that accidentally ended up inside a Textures sub-folder
        if "Textures" in cgamat.parts:
            continue

        rel = cgamat.relative_to(MATERIALS_ROOT)
        category, subcategory, group = _classify(rel)

        props       = parse_cgamat(cgamat)
        preview_url = find_preview(cgamat)

        results.append({
            "id":           str(rel).replace("\\", "/"),
            "category":     category,
            "subcategory":  subcategory,           # e.g. "Cladding" or "Road" or ""
            "group":        group,                 # e.g. "Corrugated" or "Asphalt"
            "name":         props["name"],
            "preview_url":  preview_url,
            "props":        props,
        })

    return results


MATERIAL_INDEX: list[dict] = []

@app.on_event("startup")
def on_startup():
    global MATERIAL_INDEX
    MATERIAL_INDEX = scan_materials()
    print(f"[Material API] Loaded {len(MATERIAL_INDEX)} materials from {MATERIALS_ROOT}")


# ── Category tree ─────────────────────────────────────────────────────────────

@app.get("/materials/categories")
def list_categories():
    """
    Returns a 3-level tree:
    {
      "Architectural": {
        "Cladding": ["Corrugated", "Aluminium", ...],
        "Walls":    ["Brick", "Concrete", ...]
      },
      "Generic": {
        "": ["Asphalt", "Glass", "Metal", ...]
      },
      ...
    }
    """
    tree: Dict[str, Dict[str, set]] = {}
    for m in MATERIAL_INDEX:
        cat = m["category"]
        sub = m["subcategory"]
        grp = m["group"]
        tree.setdefault(cat, {})
        tree[cat].setdefault(sub, set())
        tree[cat][sub].add(grp)

    # Convert sets to sorted lists
    return {
        cat: {sub: sorted(grps) for sub, grps in subs.items()}
        for cat, subs in sorted(tree.items())
    }


# ── Material list with filtering ─────────────────────────────────────────────

@app.get("/materials")
def list_materials(
    category:    Optional[str] = None,
    subcategory: Optional[str] = None,
    group:       Optional[str] = None,
    q:           Optional[str] = None,
):
    results = MATERIAL_INDEX
    if category:
        results = [m for m in results if m["category"].lower()    == category.lower()]
    if subcategory is not None:
        results = [m for m in results if m["subcategory"].lower() == subcategory.lower()]
    if group:
        results = [m for m in results if m["group"].lower()       == group.lower()]
    if q:
        q_lower = q.lower()
        results = [m for m in results if q_lower in m["name"].lower()]
    return {"total": len(results), "materials": results}


# ── Texture file serving ──────────────────────────────────────────────────────

@app.get("/texture/{filepath:path}")
def serve_texture(filepath: str):
    abs_path = MATERIALS_ROOT / filepath.replace("/", os.sep)
    if not abs_path.exists() or not abs_path.is_file():
        raise HTTPException(status_code=404, detail=f"Texture not found: {filepath}")
    ext = abs_path.suffix.lower().lstrip(".")    # ".jpg" → "jpg"
    media_types = {"jpg": "image/jpeg", "jpeg": "image/jpeg", "png": "image/png", "webp": "image/webp"}
    return FileResponse(str(abs_path), media_type=media_types.get(ext, "application/octet-stream"))


@app.get("/health")
def health():
    return {"status": "ok", "materials_root": str(MATERIALS_ROOT), "count": len(MATERIAL_INDEX)}