From 1a463842e3ebca64a08031c6a87c302187274c38 Mon Sep 17 00:00:00 2001
From: "Simeon H.K. Fitch" <fitch@astraea.io>
Date: Wed, 31 Jan 2024 15:47:48 -0500
Subject: [PATCH] Scaffolding for GDALWarp binding.

---
 src/raster/warp/mod.rs          | 96 +++++++++++++++++++++++++++++++--
 src/raster/warp/warp_options.rs | 48 +++++++++++++++--
 2 files changed, 138 insertions(+), 6 deletions(-)

diff --git a/src/raster/warp/mod.rs b/src/raster/warp/mod.rs
index cce886ce..a560b77b 100644
--- a/src/raster/warp/mod.rs
+++ b/src/raster/warp/mod.rs
@@ -9,11 +9,11 @@ mod reproject_options;
 mod resample;
 mod warp_options;
 
-use gdal_sys::CPLErr;
+use gdal_sys::{CPLErr, GDALDatasetH, GDALWarp};
 pub use reproject_options::*;
 pub use resample::*;
 use std::ffi::CString;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::ptr;
 pub use warp_options::*;
 
@@ -22,7 +22,7 @@ use crate::DriverManager;
 
 use crate::errors::*;
 use crate::spatial_ref::SpatialRef;
-use crate::utils::{_last_cpl_err, _path_to_c_string};
+use crate::utils::{_last_cpl_err, _last_null_pointer_err, _path_to_c_string};
 
 /// Reproject raster dataset into the given [`SpatialRef`] and save result to `dst_file`.
 pub fn create_and_reproject<P: AsRef<Path>>(
@@ -163,6 +163,79 @@ pub fn reproject_into(
     Ok(())
 }
 
+pub fn warp<D>(source: &Dataset, dest: D, options: &GdalWarpOptions) -> Result<Dataset>
+where
+    D: Into<WarpDestination>,
+{
+    warp_multiple(&[source], dest, options)
+}
+
+pub fn warp_multiple<D>(source: &[&Dataset], dest: D, options: &GdalWarpOptions) -> Result<Dataset>
+where
+    D: Into<WarpDestination>,
+{
+    let app_opts = GdalWarpAppOptions::default();
+
+    if true {
+        todo!("how the hell do you go from {options:?} to GdalWarpAppOptions?");
+    }
+
+    let mut source = source.iter().map(|ds| ds.c_dataset()).collect::<Vec<_>>();
+
+    let dest = dest.into();
+    match dest {
+        WarpDestination::Dataset(ds) => {
+            let ds_c = unsafe {
+                GDALWarp(
+                    ptr::null_mut(),
+                    ds.c_dataset(),
+                    source.len() as libc::c_int,
+                    source.as_mut_ptr(),
+                    app_opts.as_ptr(),
+                    ptr::null_mut(),
+                )
+            };
+            if ds_c.is_null() {
+                Err(_last_null_pointer_err("GDALWarp"))
+            } else {
+                Ok(ds)
+            }
+        }
+        WarpDestination::Path(p) => {
+            let path = _path_to_c_string(&p)?;
+            let ds_c = unsafe {
+                GDALWarp(
+                    path.as_ptr(),
+                    ptr::null_mut(),
+                    source.len() as libc::c_int,
+                    source.as_ptr() as *mut GDALDatasetH,
+                    app_opts.as_ptr(),
+                    ptr::null_mut(),
+                )
+            };
+            Ok(unsafe { Dataset::from_c_dataset(ds_c) })
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum WarpDestination {
+    Dataset(Dataset),
+    Path(PathBuf),
+}
+
+impl From<Dataset> for WarpDestination {
+    fn from(ds: Dataset) -> Self {
+        WarpDestination::Dataset(ds)
+    }
+}
+
+impl From<PathBuf> for WarpDestination {
+    fn from(path: PathBuf) -> Self {
+        WarpDestination::Path(path)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -251,4 +324,21 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    #[ignore]
+    fn test_warp() -> Result<()> {
+        let source = TempFixture::fixture("labels.tif");
+        let source_ds = Dataset::open(&source)?;
+        let dest = Path::new("target").join("labels-warp.tif");
+
+        let mut options = GdalWarpOptions::default();
+        options
+            .with_band_count(source_ds.raster_count())
+            .with_initial_value(InitValue::NoData)
+            .with_resampling_alg(WarpResampleAlg::NearestNeighbour);
+
+        warp(&source_ds, dest, &options)?;
+        Ok(())
+    }
 }
diff --git a/src/raster/warp/warp_options.rs b/src/raster/warp/warp_options.rs
index b70a6b90..fc9625bc 100644
--- a/src/raster/warp/warp_options.rs
+++ b/src/raster/warp/warp_options.rs
@@ -1,4 +1,5 @@
 use std::fmt::{Debug, Display, Formatter};
+use std::ptr;
 use std::ptr::NonNull;
 
 use crate::cpl::CslStringList;
@@ -9,9 +10,9 @@ use crate::utils::_last_null_pointer_err;
 use crate::xml::GdalXmlNode;
 use gdal_sys::{
     GDALCloneWarpOptions, GDALCreateWarpOptions, GDALDeserializeWarpOptions,
-    GDALDestroyWarpOptions, GDALSerializeWarpOptions, GDALWarpInitDefaultBandMapping,
-    GDALWarpInitDstNoDataReal, GDALWarpInitSrcNoDataReal, GDALWarpOptions,
-    GDALWarpResolveWorkingDataType,
+    GDALDestroyWarpOptions, GDALSerializeWarpOptions, GDALWarpAppOptions, GDALWarpAppOptionsFree,
+    GDALWarpAppOptionsNew, GDALWarpInitDefaultBandMapping, GDALWarpInitDstNoDataReal,
+    GDALWarpInitSrcNoDataReal, GDALWarpOptions, GDALWarpResolveWorkingDataType,
 };
 use libc::c_char;
 
@@ -246,6 +247,47 @@ impl Debug for GdalWarpOptions {
     }
 }
 
+#[derive(Debug)]
+pub struct GdalWarpAppOptions(NonNull<GDALWarpAppOptions>);
+
+impl GdalWarpAppOptions {
+    /// Instatiate and empty set of warp options.
+    pub fn new() -> Self {
+        unsafe { Self::from_ptr(GDALWarpAppOptionsNew(ptr::null_mut(), ptr::null_mut())) }
+    }
+
+    /// Create Self from a raw pointer.
+    ///
+    /// # Safety
+    /// Caller is responsible for ensuring `ptr` is not null, and
+    /// ownership of `ptr` is properly transferred
+    pub unsafe fn from_ptr(ptr: *mut GDALWarpAppOptions) -> Self {
+        Self(NonNull::new_unchecked(ptr))
+    }
+
+    /// Get a immutable pointer to C API options.
+    pub fn as_ptr(&self) -> *const GDALWarpAppOptions {
+        self.0.as_ptr()
+    }
+
+    /// Get a mutable pointer to C API options.
+    pub fn as_ptr_mut(&mut self) -> *mut GDALWarpAppOptions {
+        self.0.as_ptr()
+    }
+}
+
+impl Drop for GdalWarpAppOptions {
+    fn drop(&mut self) {
+        unsafe { GDALWarpAppOptionsFree(self.as_ptr_mut()) }
+    }
+}
+
+impl Default for GdalWarpAppOptions {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 /// Specifies the initial value cells in the destination dataset during a warp operation.
 ///
 /// See [`GdalWarpOptions::with_initial_value`].