"""
RockGlacierNet — single source of truth for DATA COLLECTION + PATCH BUILDING.

Everything the collection/patching pipeline writes lives under `patch_dataset/`.
Edit values here; no other file needs touching to re-collect at a different
patch size or with a different context window.

Pipeline (Option A — enlarged per-glacier window):
    1. preprocess/collect_features.py   shapefile -> patch_dataset/raw/{features,masks}   (run on Windows: needs ee+geopandas)
    2. preprocess/build_patches.py      raw/      -> patch_dataset/patches_{size}/{split}  (run anywhere: needs rasterio)

Why Option A: the old 200 m buffer produced tiles whose median size is 83 px, so
86% were smaller than a 128 px patch — a 128 patch on them would be mostly
reflect-padding. We instead download a generous context window ONCE (big enough
for the largest target patch) and tile locally to any size in PATCH_SIZES.
"""

from pathlib import Path

# ── Roots ─────────────────────────────────────────────────────────────────────
# config.py lives in <project>/patch_dataset/ , so:
PATCH_DATASET_DIR = Path(__file__).resolve().parent          # .../patch_dataset
PROJECT_ROOT      = PATCH_DATASET_DIR.parent                 # .../RockGlacierNet

# Input shapefile (rock-glacier inventory polygons). Override on Windows.
SHAPEFILE_PATH = PROJECT_ROOT / "Final_merged01" / "Final_merged01.shp"

# All COLLECTED + BUILT artifacts stay inside patch_dataset/ (and nowhere else).
RAW_DIR          = PATCH_DATASET_DIR / "raw"
RAW_FEATURES_DIR = RAW_DIR / "features"      # feature_XXXX.tif  (12-band)  [per-glacier, legacy]
RAW_MASKS_DIR    = RAW_DIR / "masks"         # mask_XXXX.tif     (1-band, pixel-aligned)

# Region pipeline (whole-Sikkim grid) output — used by collect_region.py.
RAW_REGION_DIR          = PATCH_DATASET_DIR / "raw_region"
RAW_REGION_FEATURES_DIR = RAW_REGION_DIR / "features"   # tile_RRRR_CCCC.tif  (12-band)
RAW_REGION_MASKS_DIR    = RAW_REGION_DIR / "masks"      # tile_RRRR_CCCC.tif  (1-band, aligned)

# Enlarged per-glacier pipeline output — used by collect_glacier.py.
# One crop per inventory polygon, glacier centered, with real context (not padding).
RAW_GLACIER_DIR          = PATCH_DATASET_DIR / "raw_glacier"
RAW_GLACIER_FEATURES_DIR = RAW_GLACIER_DIR / "features"  # feature_XXXX.tif (12-band)
RAW_GLACIER_MASKS_DIR    = RAW_GLACIER_DIR / "masks"     # mask_XXXX.tif    (1-band, aligned)
# Buffer added around each polygon bbox. 400 m makes a typical crop ~128 px: the
# glacier stays prominent (~10-15% positive, like the working dataset/) while its
# border is REAL terrain instead of the zero-padding the old dataset/ used.
GLACIER_BUFFER_M = 400.0

# ── Geometry / projection ─────────────────────────────────────────────────────
TARGET_CRS = "EPSG:32645"   # UTM Zone 45N (metres) — Sikkim
SCALE_M    = 10.0           # output pixel size (metres). Sentinel-2 native 10 m.

# ── Patch sizes ───────────────────────────────────────────────────────────────
PATCH_SIZES   = [64, 128, 256]   # sizes you may build from the SAME raw download
DEFAULT_PATCH = 128              # used when build_patches.py is run with no --patch-size

# Context window downloaded per glacier (metres added on every side of the
# polygon bbox). Must be >= (max(PATCH_SIZES)/2)*SCALE_M so even a tiny glacier
# yields a tile large enough to hold the biggest patch. For 256 px that is 1280 m.
CONTEXT_BUFFER_M = (max(PATCH_SIZES) // 2) * SCALE_M + 50.0   # = 1330 m

# ── Region (whole-Sikkim) collection ──────────────────────────────────────────
# AOI = bounding box of all inventory polygons (= essentially the Sikkim glacier
# belt, ~7130 km^2), expanded by AOI_MARGIN_M. The AOI is gridded into square
# download tiles of RAW_TILE_PX px; each tile is downloaded as one 12-band GeoTIFF.
AOI_MARGIN_M  = 1000.0    # expand the glacier-bbox AOI by this on every side
RAW_TILE_PX   = 512       # download-tile size (px). 512 @ 10 m = 5.12 km, ~8 MB/tile (safe < 32 MB GEE limit)
# Which grid tiles to download:
#   "sampled" → every tile touching a glacier + REGION_BG_KEEP of background tiles (good training set)
#   "dense"   → every tile in the AOI (full Sikkim mosaic; for region-wide inference). Multi-GB.
REGION_MODE      = "sampled"
REGION_BG_KEEP   = 0.25   # (sampled mode) fraction of pure-background tiles to also download
S2_CLOUD_PCT     = 20     # scene-level CLOUDY_PIXEL_PERCENTAGE filter — keeps the median composite
                          # light enough to avoid GEE "User memory limit exceeded" on download.

# ── Patch extraction ──────────────────────────────────────────────────────────
STRIDE_FRACTION         = 0.5    # patch overlap; stride = round(patch_size * this)
BACKGROUND_KEEP_RATIO   = 0.05   # fraction of pure-background patches to keep
MIN_GLACIER_PERCENTAGE  = 2.0    # keep any patch with > this % glacier pixels
PADDING_MODE            = "reflect"   # "reflect" | "constant" (0-fill)

# ── Train / val / test split (by SOURCE GLACIER — prevents patch leakage) ─────
SPLIT_RATIOS = {"train": 0.70, "val": 0.15, "test": 0.15}
RANDOM_SEED  = 42

# ── Bands ─────────────────────────────────────────────────────────────────────
# ORDER IS CONTRACTUAL: must match data_generator.GLOBAL_MEAN / GLOBAL_STD.
NUM_BANDS  = 12
BAND_NAMES = ["B2", "B3", "B4", "B8", "B11", "B12",
              "NDVI", "NDWI", "NDSI", "Elev", "Slope", "Aspect"]

# ── Earth Engine collection settings (used by collect_features.py) ────────────
GEE_PROJECT       = "rock-glacier-net"
S2_COLLECTION     = "COPERNICUS/S2_SR_HARMONIZED"
DEM_COLLECTION    = "COPERNICUS/DEM/GLO30"
S2_DATE_START     = "2021-01-01"
S2_DATE_END       = "2024-01-01"
S2_SR_DIVISOR     = 10000.0      # scale Sentinel-2 SR DN -> reflectance
NODATA_VALUE      = -9999


# ── Derived helpers ───────────────────────────────────────────────────────────
def stride_for(patch_size: int) -> int:
    """Step between patch origins for a given patch size."""
    return max(1, round(patch_size * STRIDE_FRACTION))


def patches_dir(patch_size: int) -> Path:
    """Output root for a given patch size, e.g. patch_dataset/patches_128/."""
    return PATCH_DATASET_DIR / f"patches_{patch_size}"


def as_dict(patch_size: int) -> dict:
    """Flat config snapshot written into each build's metadata/config.json."""
    return {
        "patch_size":             patch_size,
        "stride":                 stride_for(patch_size),
        "stride_fraction":        STRIDE_FRACTION,
        "scale_m":                SCALE_M,
        "context_buffer_m":       CONTEXT_BUFFER_M,
        "background_keep_ratio":  BACKGROUND_KEEP_RATIO,
        "minimum_glacier_pct":    MIN_GLACIER_PERCENTAGE,
        "padding_mode":           PADDING_MODE,
        "split_ratios":           SPLIT_RATIOS,
        "random_seed":            RANDOM_SEED,
        "target_crs":             TARGET_CRS,
        "num_bands":              NUM_BANDS,
        "band_names":             BAND_NAMES,
        "raw_features_dir":       str(RAW_FEATURES_DIR),
        "raw_masks_dir":          str(RAW_MASKS_DIR),
        "output_dir":             str(patches_dir(patch_size)),
    }