// SPDX-License-Identifier: MPL-2.0
#pragma once
#include "aare/CalculateEta.hpp"
#include "aare/ClusterFile.hpp"
#include "aare/defs.hpp"

#include <cstdint>
#include <filesystem>
#include <pybind11/iostream.h>
#include <pybind11/numpy.h>
#include <pybind11/pybind11.h>
#include <pybind11/stl.h>
#include <pybind11/stl/filesystem.h>
#include <string>
#include <utility>

namespace py = pybind11;
using namespace ::aare;

template <typename Range> class ClusterFileIterator {
    Range m_range;
    std::optional<typename Range::Iterator> m_iterator;
    bool m_done{false};

  public:
    explicit ClusterFileIterator(Range range) : m_range(std::move(range)) {}

    typename Range::Iterator::value_type next() {
        if (m_done) {
            throw py::stop_iteration();
        }
        // Advance before returning the next result, never after yielding it.
        if (m_iterator) {
            ++*m_iterator;
        } else {
            m_iterator.emplace(m_range.begin());
        }
        if (*m_iterator == m_range.end()) {
            m_done = true;
            throw py::stop_iteration();
        }
        return std::move(**m_iterator);
    }
};

template <typename Iterator>
void define_cluster_file_iterator(py::module &m, const std::string &name) {
    py::class_<Iterator>(m, name.c_str())
        .def(
            "__iter__", [](Iterator &self) -> Iterator & { return self; },
            py::return_value_policy::reference_internal)
        .def("__next__", &Iterator::next);
}

template <typename Type, uint8_t CoordSizeX, uint8_t CoordSizeY,
          typename CoordType = uint16_t>
void define_ClusterFile(py::module &m, const std::string &typestr) {

    using ClusterType = Cluster<Type, CoordSizeX, CoordSizeY, CoordType>;
    using File = ClusterFile<ClusterType>;
    using FrameIterator = ClusterFileIterator<typename File::FrameRange>;
    using ChunkIterator = ClusterFileIterator<typename File::ChunkRange>;

    auto class_name = fmt::format("ClusterFile_{}", typestr);
    define_cluster_file_iterator<FrameIterator>(m,
                                                class_name + "_FrameIterator");
    define_cluster_file_iterator<ChunkIterator>(m,
                                                class_name + "_ChunkIterator");

    py::class_<ClusterFile<ClusterType>>(
        m, class_name.c_str(),
        "Read and write legacy binary cluster files. The format contains no "
        "cluster type or shape metadata, so this class must match the file.")
        .def(py::init<const std::filesystem::path &, size_t,
                      const std::string &>(),
             py::arg("fname"), py::arg("chunk_size") = 1000,
             py::arg("mode") = "r",
             "Open a cluster file. Mode must be 'r' to read, 'w' to truncate "
             "and write, or 'a' to append.")
        .def(
            "frames", [](File &self) { return FrameIterator(self.frames()); },
            py::keep_alive<0, 1>(),
            "Iterate over complete frames from the current position, including "
            "empty and fully filtered frames with their stored frame numbers. "
            "Results own their storage. The iterator keeps the file alive but "
            "shares its cursor; use only one traversal at a time.")
        .def(
            "chunks", [](File &self) { return ChunkIterator(self.chunks()); },
            py::keep_alive<0, 1>(),
            "Iterate from the current position using the constructor's chunk "
            "size, which must be positive. Results own their storage. The "
            "iterator keeps the file alive but shares its cursor; use only "
            "one traversal at a time.")
        .def(
            "chunks",
            [](File &self, size_t chunk_size) {
                return ChunkIterator(self.chunks(chunk_size));
            },
            py::arg("chunk_size"), py::keep_alive<0, 1>(),
            "Iterate over chunks of up to chunk_size selected clusters. The "
            "size must be positive and does not change the constructor's "
            "default. Chunks may span frames; their frame numbers are not "
            "per-cluster metadata. Only the final chunk can be short.")
        .def(
            "read_clusters",
            [](ClusterFile<ClusterType> &self, size_t n_clusters) {
                auto v = new ClusterVector<ClusterType>(
                    self.read_clusters(n_clusters));
                return v;
            },
            py::return_value_policy::take_ownership, py::arg("n_clusters"),
            "Read up to n_clusters without preserving frame boundaries. The "
            "result may combine frames, so its frame number is not reliable "
            "per-cluster metadata.")
        .def(
            "read_frame",
            [](ClusterFile<ClusterType> &self) -> py::object {
                auto clusters = self.read_frame();
                if (!clusters) {
                    return py::none();
                }
                return py::cast(
                    new ClusterVector<ClusterType>(std::move(*clusters)),
                    py::return_value_policy::take_ownership);
            },
            "Read and return the next complete frame with its frame number, "
            "or None at end of file.")
        .def("set_roi", &ClusterFile<ClusterType>::set_roi, py::arg("roi"),
             "Select clusters whose centers lie within the half-open ROI.")
        .def("tell", &ClusterFile<ClusterType>::tell,
             "Return the current byte position in the file.")
        .def("estimate_n_clusters",
             &ClusterFile<ClusterType>::estimate_n_clusters,
             "Estimate the number of clusters from the file size. Frame "
             "headers can make this larger than the actual count.")
        .def(
            "set_noise_map", // conversions ok
            [](ClusterFile<ClusterType> &self,
               py::array_t<int32_t, py::array::c_style | py::array::forcecast>
                   noise_map) {
                auto view = make_view_2d(noise_map);
                self.set_noise_map(view);
            },
            py::arg("noise_map"),
            "Set a two-dimensional, C-contiguous int32 noise map indexed as "
            "[y, x]. The map must cover every cluster center coordinate.")

        .def(
            "set_gain_map", // conversions ok
            [](ClusterFile<ClusterType> &self,
               py::array_t<double, py::array::c_style | py::array::forcecast>
                   gain_map) {
                auto view = make_view_2d(gain_map);
                self.set_gain_map(view);
            },
            py::arg("gain_map"),
            "Set a two-dimensional, C-contiguous float64 gain map in "
            "ADU/energy, indexed as [y, x]. Clusters whose complete footprint "
            "extends beyond the map are retained with all data values set to "
            "zero.")

        .def("close", &ClusterFile<ClusterType>::close,
             "Close the file. Calling close more than once is safe.")
        .def("write_frame", &ClusterFile<ClusterType>::write_frame,
             py::arg("clusters"),
             "Write one ClusterVector, including its frame number.")
        .def("__enter__", [](ClusterFile<ClusterType> &self) { return &self; })
        .def("__exit__",
             [](ClusterFile<ClusterType> &self,
                [[maybe_unused]] const std::optional<pybind11::type> &exc_type,
                [[maybe_unused]] const std::optional<pybind11::object>
                    &exc_value,
                [[maybe_unused]] const std::optional<pybind11::object>
                    &traceback) { self.close(); })
        .def("__iter__", [](ClusterFile<ClusterType> &self) { return &self; })
        .def("__next__",
             [](File &self) { return ChunkIterator(self.chunks()).next(); });
}