// File adapted from dear-imgui's ImVector, implemented in https://github.com/ocornut/imgUI/blob/master/imgui.h
#pragma once

#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <span>

template <class T>
class PodVector {
public:
	using value_type = T;
	using iterator = value_type*;
	using const_iterator = const value_type*;

private:
	int mSize;
	int mCapacity;
	T* mData;

public:
	PodVector() {
		mSize = mCapacity = 0;
		mData = nullptr;
	}

	PodVector(const PodVector<T>& src) {
		mSize = mCapacity = 0;
		mData = nullptr;
		operator=(src);
	}

	PodVector<T>& operator=(const PodVector<T>& src) {
		clear();
		resize(src.mSize);
		std::memcpy(mData, src.mData, (size_t)mSize * sizeof(T));
		return *this;
	}

	PodVector(PodVector&& src) {
		mSize = src.mSize;
		mCapacity = src.mCapacity;
		mData = src.mData;

		src.mSize = src.mCapacity = 0;
		src.mData = nullptr;
	}

	PodVector& operator=(PodVector&& src) {
		if (this != &src) {
			std::free(mData);

			mSize = src.mSize;
			mCapacity = src.mCapacity;
			mData = src.mData;

			src.mSize = src.mCapacity = 0;
			src.mData = nullptr;
		}
		return *this;
	}

	~PodVector() {
		std::free(mData);
	}

	bool empty() const { return mSize == 0; }
	int size() const { return mSize; }
	int size_in_bytes() const { return mSize * (int)sizeof(T); }
	int max_size() const { return 0x7FFFFFFF / (int)sizeof(T); }
	int capacity() const { return mCapacity; }

	T& operator[](int i) {
		assert(i >= 0 && i < mSize);
		return mData[i];
	}

	const T& operator[](int i) const {
		assert(i >= 0 && i < mSize);
		return mData[i];
	}

	void clear() {
		if (mData) {
			mSize = mCapacity = 0;
			std::free(mData);
			mData = nullptr;
		}
	}

	T* begin() { return mData; }
	const T* begin() const { return mData; }
	T* end() { return mData + mSize; }
	const T* end() const { return mData + mSize; }

	T& front() {
		assert(mSize > 0);
		return mData[0];
	}

	const T& front() const {
		assert(mSize > 0);
		return mData[0];
	}

	T& back() {
		assert(mSize > 0);
		return mData[mSize - 1];
	}

	const T& back() const {
		assert(mSize > 0);
		return mData[mSize - 1];
	}

	void swap(PodVector<T>& rhs) {
		int rhs_size = rhs.mSize;
		rhs.mSize = mSize;
		mSize = rhs_size;
		int rhs_cap = rhs.mCapacity;
		rhs.mCapacity = mCapacity;
		mCapacity = rhs_cap;
		T* rhs_mDataTmp = rhs.mData;
		rhs.mData = mData;
		mData = rhs_mDataTmp;
	}

	int grow_capacity(int sz) const {
		int newCapacity = mCapacity ? (mCapacity + mCapacity / 2) : 8;
		return newCapacity > sz ? newCapacity : sz;
	}

	void resize(int new_size) {
		if (new_size > mCapacity) reserve(grow_capacity(new_size));
		mSize = new_size;
	}

	void resize_more(int size) {
		resize(mSize + size);
	}

	void resize(int new_size, const T& v) {
		if (new_size > mCapacity) reserve(grow_capacity(new_size));
		if (new_size > mSize) {
			for (int n = mSize; n < new_size; n++) {
				std::memcpy(&mData[n], &v, sizeof(v));
			}
		}
		mSize = new_size;
	}

	void resize_more(int size, const T& v) {
		resize(mSize + size, v);
	}

	void shrink(int new_size) {
		assert(new_size <= mSize);
		mSize = new_size;
	}

	/// Resize a vector to a smaller mSize, guaranteed not to cause a reallocation
	void reserve(int newCapacity) {
		if (newCapacity <= mCapacity) return;
		auto tmp = (T*)std::malloc((size_t)newCapacity * sizeof(T));
		if (mData) {
			std::memcpy(tmp, mData, (size_t)mSize * sizeof(T));
			std::free(mData);
		}
		mData = tmp;
		mCapacity = newCapacity;
	}

	void reserve_more(int size) {
		reserve(mSize + size);
	}

	/// NB: It is illegal to call push_back/push_front/insert with a reference pointing inside the PodVector data itself! e.g. v.push_back(v[10]) is forbidden.
	void push_back(const T& v) {
		if (mSize == mCapacity) reserve(grow_capacity(mSize + 1));
		std::memcpy(&mData[mSize], &v, sizeof(v));
		mSize++;
	}

	void pop_back() {
		assert(mSize > 0);
		mSize--;
	}

	void push_front(const T& v) {
		if (mSize == 0) {
			push_back(v);
		} else {
			insert(mData, v);
		}
	}

	T* erase(const T* it) {
		assert(it >= mData && it < mData + mSize);
		const ptrdiff_t off = it - mData;
		std::memmove(mData + off, mData + off + 1, ((size_t)mSize - (size_t)off - 1) * sizeof(T));
		mSize--;
		return mData + off;
	}

	T* erase(const T* it, const T* it_last) {
		assert(it >= mData && it < mData + mSize && it_last > it && it_last <= mData + mSize);
		const ptrdiff_t count = it_last - it;
		const ptrdiff_t off = it - mData;
		std::memmove(mData + off, mData + off + count, ((size_t)mSize - (size_t)off - count) * sizeof(T));
		mSize -= (int)count;
		return mData + off;
	}

	T* erase_unsorted(const T* it) {
		assert(it >= mData && it < mData + mSize);
		const ptrdiff_t off = it - mData;
		if (it < mData + mSize - 1) std::memcpy(mData + off, mData + mSize - 1, sizeof(T));
		mSize--;
		return mData + off;
	}

	T* insert(const T* it, const T& v) {
		assert(it >= mData && it <= mData + mSize);
		const ptrdiff_t off = it - mData;
		if (mSize == mCapacity) reserve(grow_capacity(mSize + 1));
		if (off < (int)mSize) std::memmove(mData + off + 1, mData + off, ((size_t)mSize - (size_t)off) * sizeof(T));
		std::memcpy(&mData[off], &v, sizeof(v));
		mSize++;
		return mData + off;
	}

	bool contains(const T& v) const {
		const T* data = mData;
		const T* dataEnd = mData + mSize;
		while (data < dataEnd) {
			if (*data++ == v) return true;
		}
		return false;
	}

	T* find(const T& v) {
		T* data = mData;
		const T* dataEnd = mData + mSize;
		while (data < dataEnd)
			if (*data == v)
				break;
			else
				++data;
		return data;
	}

	const T* find(const T& v) const {
		const T* data = mData;
		const T* dataEnd = mData + mSize;
		while (data < dataEnd)
			if (*data == v)
				break;
			else
				++data;
		return data;
	}

	bool find_erase(const T& v) {
		const T* it = find(v);
		if (it < mData + mSize) {
			erase(it);
			return true;
		}
		return false;
	}

	bool find_erase_unsorted(const T& v) {
		const T* it = find(v);
		if (it < mData + mSize) {
			erase_unsorted(it);
			return true;
		}
		return false;
	}

	int index_from_ptr(const T* it) const {
		assert(it >= mData && it < mData + mSize);
		const ptrdiff_t off = it - mData;
		return (int)off;
	}

	// Custom utility functions

	std::span<T> as_span() { return { mData, (size_t)mSize }; }
	std::span<uint8_t> as_data_span() { return { (uint8_t*)mData, (size_t)mSize * sizeof(T) }; }
	std::span<const T> as_span() const { return { mData, (size_t)mSize }; }
	std::span<const uint8_t> as_data_span() const { return { (uint8_t*)mData, (size_t)mSize * sizeof(T) }; }
};