Add download_tiles.py script, and tweak params in notebook

Adds a script that reproduces the section of the notebook where it downloads
all the tiles, slightly modified to run on the command line.

mosaic.ipynb

@@ -215,12 +215,13 @@
     "\n",
     "tiler_url = \"https://tiler.staging.modelmywatershed.org\"\n",
     "tiler_lambda_function_url = \"https://2empcsyg6p3r53jhbp6v2ovsia0awpdn.lambda-url.us-west-2.on.aws\"\n",
-    "\n",
-    "lambda_tile_url_template = tile_url_template.replace(tiler_url,tiler_lambda_function_url)\n",
     "zoom_levels = [4,5]\n",
-    "scales = [\"@2x\",]  # Could also do \"\" and \"@1x\" (which both produce 1x tiles, but with different hashes)\n",
+    "scales = [\"\",]  # Options are \"@2\", \"@1x\", and \"\" (which also produces 1x tiles, but with different hashes)\n",
     "output_dir = \"tiles\"\n",
     "\n",
+    "\n",
+    "lambda_tile_url_template = tile_url_template.replace(tiler_url,tiler_lambda_function_url)\n",
+    "\n",
     "@request_concurrency_limit_decorator(limit=20)\n",
     "async def download_tile(tile_url_template: str, z: int, x: int, y: int):\n",
     "    base_tile_url = tile_url_template.replace(\"{z}\", str(z)).replace(\"{x}\", str(x)).replace(\"{y}\", str(y))\n",

scripts/download_tiles.py

@@ -0,0 +1,78 @@
+import asyncio
+import httpx
+import aiofiles
+import aiofiles.os
+import hashlib
+import os
+from pathlib import Path
+
+# This is a version of the main loop from the 'mosaic.ipnb' notebook, but tweaked to run from
+# the command line. It will download all tiles for the given zoom_levels.
+# The parameters are hard-coded at the top of the file here, not passed in (since that's easier
+# to write and keeps it more similar to the notebook).
+
+COLORMAP = "%7B%220%22%3A%20%22%23000000%22%2C%20%221%22%3A%20%22%23419bdf%22%2C%20%222%22%3A%20%22%23397d49%22%2C%20%223%22%3A%20%22%23000000%22%2C%20%224%22%3A%20%22%237a87c6%22%2C%20%225%22%3A%20%22%23e49635%22%2C%20%226%22%3A%20%22%23000000%22%2C%20%227%22%3A%20%22%23c4281b%22%2C%20%228%22%3A%20%22%23a59b8f%22%2C%20%229%22%3A%20%22%23a8ebff%22%2C%20%2210%22%3A%20%22%23616161%22%2C%20%2211%22%3A%20%22%23e3e2c3%22%7D"
+
+# the 2023 one
+tile_url_template = "https://tiler.staging.modelmywatershed.org/mosaicjson/mosaics/fec54b55-5e75-4c6d-ac47-41579d722dab/tiles/{z}/{x}/{y}"
+
+tiler_url = "https://tiler.staging.modelmywatershed.org"
+tiler_lambda_function_url = "https://2empcsyg6p3r53jhbp6v2ovsia0awpdn.lambda-url.us-west-2.on.aws"
+zoom_levels = [4,5]
+scales = ["",]  # Options are "@2", "@1x", and "" (which also produces 1x tiles, but with different hashes)
+output_dir = "tiles-lambda"
+
+
+# From here: https://stackoverflow.com/a/66289885
+from functools import wraps
+def request_concurrency_limit_decorator(limit=3):
+    # Bind the default event loop 
+    sem = asyncio.Semaphore(limit)
+    def executor(func):
+        @wraps(func)
+        async def wrapper(*args, **kwargs):
+            async with sem:
+                return await func(*args, **kwargs)
+        return wrapper
+    return executor
+
+
+lambda_tile_url_template = tile_url_template.replace(tiler_url,tiler_lambda_function_url)
+
+
+@request_concurrency_limit_decorator(limit=30)
+async def download_tile(tile_url_template: str, z: int, x: int, y: int):
+    base_tile_url = tile_url_template.replace("{z}", str(z)).replace("{x}", str(x)).replace("{y}", str(y))
+    mosaic_path = base_tile_url.split("/mosaicjson/mosaics/", maxsplit=1)[1]
+    for scale in scales:
+        params = f"{scale}.png?colormap={COLORMAP}"
+        tile_url = f"{base_tile_url}{params}"
+        mosaic_hash = hashlib.sha256(params.encode()).hexdigest()
+        local_path = f"{output_dir}/{mosaic_path}/{mosaic_hash}.png"
+        if not Path(local_path).exists():
+            async with httpx.AsyncClient() as client:
+                print(f"requesting tile {tile_url}")
+                r = await client.get(tile_url, timeout=httpx.Timeout(5.0, read=900))
+                match r.status_code:
+                    case httpx.codes.OK:
+                        await aiofiles.os.makedirs(f"{output_dir}/{mosaic_path}", exist_ok=True)
+                        async with aiofiles.open(local_path, "wb") as f:
+                            await f.write(r.content)
+                    case httpx.codes.NOT_FOUND:
+                        await aiofiles.os.makedirs(f"{output_dir}/{mosaic_path}", exist_ok=True)
+                        await aiofiles.open(local_path, "w+")
+                    case _:
+                        return f"Error: {tile_url} => {r.status_code}: {r.text}"
+
+@request_concurrency_limit_decorator(limit=1)
+async def download_tiles_for_zoomlevel(zoom_level):
+    print(f"Downloading tiles for zoomlevel {zoom_level}")
+    zxy_tuples = [(zoom_level, x, y) for x in range(0, 2**zoom_level) for y in range(0, 2**zoom_level)]
+    return await asyncio.gather(*(download_tile(lambda_tile_url_template, *args) for args in zxy_tuples))
+
+async def download_tiles():
+    return await asyncio.gather(*(download_tiles_for_zoomlevel(z) for z in zoom_levels))
+
+os.makedirs(output_dir, exist_ok=True)
+result = asyncio.run(download_tiles())
+print(f"Failures: {[r for r in result if r]}")