/*
A introduction to C11 with a str cache demo.
Attempting to showcase better conventions and constructs in C; Discovered to me as of 2025 from scouring the internet.

"C is old and flawed, but your use of it is most likely more flawed. You must have calouses to write with barbed syntax & semantics."
*/

/*
The below will be implemented within this single file.
Because of this, definitions will be kept on a need-to-have basis to target only one vendor target and toolchain.
We will not use nearly any libraries and will be targeting only Windows 11 x64 using MSVC.

Even so the constructs defined and their dependencies can be properly abstracted into a ergonomic library for multiple targets with enough time and pain.
The difference is just more preprocess conditionals, and how far a library is trying to support a larger range of targets and their age discrpancy.
The more minimal the less cruft.

Definitions are defined linearly on the file on-demand as needed. Since the file is to be read linearly.
This will cause non-categorical organization so it will be more difficult to sift through if you wanted
to see definitions related to a sepecific kind of data or operation (strings, memory, etc).
*/
#if 0
int main()
{
	VArena   cache_arena; varena_init(cache_arena);	
	StrCache cache = strcache_init(varena_ainfo(cache));

	VArena      file_arena; varena_init(file_arena);
	Str         path_text = lit("../demo.strcache.c");
	FileContent text_file = file_read_contents(varena_ainfo(file_arena), path_text);

	Arena ast_arena; arena_init(ast_arena);

	WATL_ParseOps   ops    = { .str_cache = &cache, .node_backing = arena_ainfo(ast_arena) }
	WATL_ParsedInfo parsed = watl_parse(text_file.content, ops);

	watl_dbg_dump(parsed.root);
	strcache_dbg_listing(cache);
	return 0;
}
#endif

/*
The above makes use of the following core concepts to achieve its net result:
* Slices
* Arenas
* Generic Runtime Allocator Interface
* Hashing

Secondarily for the purposes of using the above sufficiently the following are also utilized:
* Virtual Address Space
* Read/Write Files
* Lexing & Parsing
* Debug printing

TODO(Ed): Do we introduce gencpp in this?
*/

/*
First thing we'll problably want is a way to deal with text effectively.
So we'll setup the the minimum for that when dealing with immutable constructs.
*/

// We'll need some minimum set of dependencies to adequately define the constructs.
// ASSUMING MODERN MSVC TOOLCHAIN.

#include <stdarg.h>
#include <stddef.h>

#include <intrin.h>
#include <tmmintrin.h>
#include <wmmintrin.h>

#include <assert.h>
// #include <stdbool.h>

typedef unsigned __int8  U8;
typedef signed   __int8  S8;
typedef unsigned __int16 U16;
typedef signed   __int16 S16;
typedef unsigned __int32 U32;
typedef signed   __int32 S32;
typedef unsigned __int64 U64;
typedef signed   __int64 S64;

typedef size_t    USIZE;
typedef ptrdiff_t SSIZE;


enum {
	false,
	true,
	true_overflow,
};

typedef S8  B8;
typedef S16 B16;
typedef S32 B32;

// Functional style cast
#define cast(type, data) ((type)(data))

#define nullptr cast(void*, 0)

// Enforces size querying uses SSIZE type.
#define size_of(data) cast(SSIZE, sizeof(data))

/*
The first construct we'll utilize is a String Slice.
In modern programming with the memory sizes utilized, it is more ergonomic to track the length of strings with their pointer.
Most strings are not stored in some immutable table tracked statically, performance loss in doing so is negligble on modern hardware constraints.
*/

typedef struct Str8 Str8;
struct Str8 {
	char const* ptr;
	SSIZE       len;
};

// String iterals in C include null-terminators, we aren't interested in preserving that.
#define lit(string_literal) (Str8){ string_literal, size_of(string_literal) - 1 }

// For now this string can visualized using a debugger.
// #define DEMO__STR_SLICE
#ifdef  DEMO__STR_SLICE
int main()
{
	Str8 first = lit("Our first string as a slice");
	return 0;
}
#endif DEMO__STR_SLICE

/*
We now want to be able to read a file. This will be a heavy rabbit-hole as we'll need to setup a basic file interface
and related definitions for handling the memory.

For the purposes of the initial definition we'll introduced fixed-sized memory handling statically allocated onto the stack.
*/

/*
First off we need to find out how to aquire the contents of a file on Windows.

We'll be wrapping the operation in a procedure called file_read_contents. We'll have it take a path and optional arguments (Opts__read_file_contents).
It will return a result in a composite struct: FileOpResult; which may be expanded as needed in the future.
*/

typedef struct FileOpResult             FileOpResult;
typedef struct Opts__read_file_contents Opts__read_file_contents;
void         api_file_read_contents(FileOpResult* result, Str8 path, Opts__read_file_contents* opts);
FileOpResult file__read_contents   (                      Str8 path, Opts__read_file_contents* opts);

#define file_read_contents(path, ...) file__read_contents(path, & (Opts__read_file_contents){__VA_ARGS__} )

/*
The file contents will be returned in bytes.
To view or manage any slice of bytes we'll be utilizing a byte slice.
*/
typedef struct SliceByte SliceByte;
struct SliceByte {
	U8*   ptr;
	SSIZE len;
};

/*
To address memory we'll use a memory slice.
*/
typedef struct SliceMem SliceMem;
struct SliceMem {
	void* ptr;
	SSIZE len;
};

/*
The above is a pattern that can be provided so that whether or not the result is formatted and provided to the user via the stack is entirely optional.
It also allows for default parameters to be defined conviently.
*/

// We'll utilize the ReadFile procedure within the WinAPI: https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-readfile
#define NOMINMAX
#define WIN32_LEAN_AND_MEAN
#define WIN32_MEAN_AND_LEAN
#define VC_EXTRALEAN
#include <windows.h>
#include <windowsx.h>
#include <timeapi.h>
#include <tlhelp32.h>
#include <Shlobj.h>
#include <processthreadsapi.h>
#pragma comment(lib, "user32")
#pragma comment(lib, "winmm")
#pragma comment(lib, "shell32")
#pragma comment(lib, "advapi32")
#pragma comment(lib, "rpcrt4")
#pragma comment(lib, "shlwapi")
#pragma comment(lib, "comctl32")
#pragma comment(linker,"\"/manifestdependency:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"") // this is required for loading correct comctl32 dll file
#undef NOMINMAX
#undef WIN32_LEAN_AND_MEAN
#undef WIN32_MEAN_AND_LEAN
#undef VC_EXTRALEAN
#if 0
BOOL ReadFile(
  [in]                HANDLE       hFile,
  [out]               LPVOID       lpBuffer,
  [in]                DWORD        nNumberOfBytesToRead,
  [out, optional]     LPDWORD      lpNumberOfBytesRead,
  [in, out, optional] LPOVERLAPPED lpOverlapped
);

// In order to read a file we need a handle to a valid filesystem entity to read from: https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea
HANDLE CreateFileA(
  [in]           LPCSTR                lpFileName,
  [in]           DWORD                 dwDesiredAccess,
  [in]           DWORD                 dwShareMode,
  [in, optional] LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  [in]           DWORD                 dwCreationDisposition,
  [in]           DWORD                 dwFlagsAndAttributes,
  [in, optional] HANDLE                hTemplateFile
);
#endif

// We need to covert our string slice to a c-string for CreateFileA's path input.

#define KILOBTYES(n) (cast(SSIZE, n) << 10)
#define MEGABYTES(n) (cast(SSIZE, n) << 20)
#define GIGABYTES(n) (cast(SSIZE, n) << 30)
#define TERABYTES(n) (cast(SSIZE, n) << 40)

/*
We'll be defining here Fixed-sized memory blocks using typedefs on-demand

They will having the following format:
typedef U8 FMem_<size>KB [ <U8 amount> ];
*/

typedef U8 FMem_16KB [ KILOBTYES(16) ];
typedef U8 FMem_64KB [ KILOBTYES(64) ];

#define typeof          __typeof__
#define fmem_slice(mem) (SliceMem) { mem, size_of(mem) }

// We'll be using an intrinsic for copying memory:
void* memory_copy(void* dest, void const* src, SSIZE length)
{
	if (dest == nullptr || src == nullptr || length == 0) {
		return nullptr;
	}
	// https://learn.microsoft.com/en-us/cpp/intrinsics/movsb?view=msvc-170
	__movsb((unsigned char*)dest, (const unsigned char*)src, length);
	return dest;
}

// Often we'll want to check validity of a slice:
#define slice_assert(slice) do {  \
	assert(slice.ptr != nullptr); \
	assert(slice.len > 0);        \
} while(0)

void slice_copy(SliceMem dest, SliceMem src) {
	assert(dest.len >= src.len);
	slice_assert(dest);
	slice_assert(src);
	memory_copy(dest.ptr, src.ptr, src.len);
}

// Assumes memory is zeroed.
char const* str8_to_cstr_capped(Str8 content, SliceMem mem) {
	assert(mem.len >= content.len);
	memory_copy(mem.ptr, content.ptr, content.len);
	return mem.ptr;
}

// To support zeroing slices we'll utilize an intrinisc.
B32 memory_zero(void* dest, SSIZE length) {
	if (dest == nullptr || length <= 0) {
		return false;
	}
	__stosd((unsigned long*)dest, 0, length);
	return true;
}

void slice_zero(SliceMem mem) {
	slice_assert(mem);
	memory_zero(mem.ptr, mem.len);
}

// Now for our "Version 1"

#define DEMO__FILE_READ_CONTENTS_V1
#ifdef  DEMO__FILE_READ_CONTENTS_V1

struct FileOpResult
{
	// For now we'll just have the content
	SliceByte content;
};

struct Opts__read_file_contents
{
	// For now we'll just have the backing memory provided as a slice.
	SliceMem backing;
	// And whether we should zero the backing.
	B32 zero_backing;
};

void api_file_read_contents(FileOpResult* result, Str8 path, Opts__read_file_contents* opts)
{
	assert(result != nullptr);
	assert(opts   != nullptr);
	slice_assert(path);
	// Backing is required at this point
	slice_assert(opts->backing);

	FMem_16KB   scratch   = {0};
	char const* path_cstr = str8_to_cstr_capped(path, fmem_slice(scratch) );

	HANDLE id_file = CreateFileA(
		path_cstr,
		GENERIC_READ,
		FILE_SHARE_READ,
		NULL,
		OPEN_EXISTING,
		FILE_ATTRIBUTE_NORMAL,
		NULL
	);
	B32 open_failed = id_file == INVALID_HANDLE_VALUE;
	if (open_failed) {
		DWORD  error_code = GetLastError();
		assert(error_code != 0);
		return;
	}

	LARGE_INTEGER file_size = {0};
	DWORD get_size_failed = ! GetFileSizeEx(id_file, & file_size);
	if   (get_size_failed) {
		assert(get_size_failed == INVALID_FILE_SIZE);
		return;
	}

	// Because we are currently using fixed size memory, we need to confirm that we can hold this content.
	B32 not_enough_backing = opts->backing.len < file_size.QuadPart;
	if (not_enough_backing) {
		assert(not_enough_backing);
		// Otherwise we don't provide a result.
		result->content = (SliceByte){0};
		return;
	}

	if (opts->zero_backing) {
		slice_zero(opts->backing);
	}

	DWORD amount_read = 0;
	BOOL read_result = ReadFile(
		id_file,
		opts->backing.ptr,
		file_size.QuadPart,
		& amount_read,
		nullptr
	);
	CloseHandle(id_file);
	
	B32 read_failed  = ! read_result;
	    read_failed |= amount_read != file_size.QuadPart;
	if (read_failed) {
		assert(read_failed);
		return;
	}

	result->content.ptr = opts->backing.ptr;
	result->content.len = file_size.QuadPart;
	return;
}

#endif DEMO__FILE_READ_CONTENTS_V1

// Version agnostic code:
inline
FileOpResult file__read_contents(Str8 path, Opts__read_file_contents* opts) {
	FileOpResult result;
	api_file_read_contents(& result, path, opts);
	return result;
}

// And now to put it all together into a test run in the debugger. Content should be properly formatted if the code is correct.
#ifdef DEMO__FILE_READ_CONTENTS_V1
int main()
{
	FMem_64KB    read_mem = {0};
	FileOpResult res      = file_read_contents(lit("demo.str_cache.c"), .backing = fmem_slice(read_mem) );
	return 0;
}
#endif