/*
 * initrd.c
 *
 *  Created on: Sep 1, 2011
 *      Author: Tiberiu
 */

#define LUXMAGIC 0xCC23AA90
#define OEMSTR "luxram"

#include <fileio.h>
#include <stdlib.h>
#include <multiboot.h>
#include <memory.h>
#include <debugio.h>
#include "initrd.h"


/**************************************
 * DEVICE 'FAKE' READ ROUTINE 		  *
 **************************************/
uint32 luxInitrdDevRead (uint32 UNUSED(offset), void* UNUSED(buffer))
{
	return LUXMAGIC;
}


/**************************************
 * OTHER USEFUL ROUTINES      		  *
 **************************************/
// Navigates and returns the directory entry that contains the file/folder
luxDirectoryEntry rootDirectoryEntry;
luxDirectoryEntry* luxGetFile (string path, uint32 data)
{
	luxHeader* head = (luxHeader*)data;
	uint32 end = strlen(path);
	uint32 start, next = 0;
	char* tmp;

	// Remove ending '/' (if any)
	if (path[end-1] == '/') --end;

	// Empty string? Return the root
	if (end == 0) {
		rootDirectoryEntry.De.Flags = 0xB68; 					// read & execute only
		rootDirectoryEntry.De.GroupId = 0; 						// system group
		rootDirectoryEntry.De.OwnerId = 0; 						// system owner
		rootDirectoryEntry.De.Size = sizeof(uint32) + head->RootSize * sizeof(luxDirectoryEntry);
		rootDirectoryEntry.Offset = (uint32)(&head->RootSize) - data; 	// calculate offset

		return &rootDirectoryEntry;
	}

	// Make sure path is correct
	if (path[0] != '/') return NULL;

	// Parse each directory until we find the one containing the file;
	uint32 cDir = (uint32)&head->RootSize;
	while (next < end)
	{
		// Parse string
		start = next + 1;	// Skip path separator
		tmp = strchr(&path[start], '/'); // Find next separator
		next = (!tmp) ? end : (uint32)(tmp - path) ; // Mark end of string, or next dir position in path

		// strchr doesn't know when to end
		if (next >= end) { tmp = 0; next = end; }

		// Look for directory
		uint32 i, find = 0xffffffff;
		uint32 size = *(uint32*)cDir;
		luxDirectoryEntry* de = (luxDirectoryEntry*) (cDir + sizeof(uint32));
		for (i = 0; i < size && find == 0xffffffff; i++)
			if (strncmp(de[i].De.Name, &path[start], strlen(de[i].De.Name)) == 0)
				find = i;

		// Not found? Nope, not good
		if (find == 0xffffffff) return NULL;

		// End of string? Return directory entry
		if (!tmp) return &de[find];

		// make sure we don't try to read a file as a folder
		if ((de[find].De.Flags & 0x7) != FileDirectory) return NULL;
		// Not end of string? Continue
		cDir = (uint32) (data + de[find].Offset);
	}

	return NULL;
}


/**************************************
 * FILE SYSTEM INTERFACE ROUTINES	  *
 **************************************/
uint32 luxDetect (MountPoint* mp)
{
	void* buffer = kmalloc(mp->BlockSize);  // must allocate a buffer for non-initrd devices...
	uint32 result = mp->Read(0, buffer);    // read something
	kfree(buffer);							// get rid of the not needed buffer

	return (result == LUXMAGIC);			// returned magic number? good
}

// Test if a file exists
DirectoryEntry* luxTest (MountPoint* mp, string path)
{
	// MountPoint.FsData[0] contains initrd image start address
	// luxDirectoryEntry contains a DirectoryEntry
	return (DirectoryEntry*) luxGetFile(path, mp->FsData[0]); // Get a directory and see
}

// Open a file
FILE* luxOpen (MountPoint* mp, FILE* f, string path)
{
	// Find it first. mp->FsData[0] contains initrd image start address.
	luxDirectoryEntry* entry = luxGetFile(path, mp->FsData[0]);

	// Invalid entry
	if (entry == NULL) return NULL;

	// Set some data fields
	f->Name = entry->De.Name;
	f->Flags = entry->De.Flags;
	f->GroupId = entry->De.GroupId;
	f->OwnerId = entry->De.OwnerId;
	f->Size = entry->De.Size;

	// Set up the buffer info. We will use these to read/write the file.
	f->BufStart = (void*) (mp->FsData[0] + entry->Offset);
	f->BufPos = f->BufStart;
	f->BufEnd = f->BufStart + entry->De.Size;

	// And return it
	return f;
}

// Close a file
FILE* luxClose (MountPoint* UNUSED(mp), FILE* f)
{
	// Just empty buffer info, so we don't attempt to read it again
	f->BufStart = f->BufPos = f->BufEnd = NULL;
	return f;
}

// Read data from a file
// Returns byte count read
uint32 luxRead (MountPoint* UNUSED(mp), FILE* f, uint32 elemsz, uint32 n, uint8* buffer)
{
	// Make sure we don't read more than we can
	uint32 total = Min(elemsz * n, (uint32)f->BufEnd - (uint32)f->BufPos);

	memcpy(buffer, f->BufPos, total);					// Copy data
	f->BufPos = (void*) ((uint32)f->BufPos + total);	// Set new buffer position
	return total;										// Return byte count read
}

// Read contents of a directory
DirectoryEntry* luxReadDir (MountPoint* UNUSED(mp), FILE* f, uint32 index)
{
	uint32 size = *(uint32*)f->BufStart;
	luxDirectoryEntry* de = (luxDirectoryEntry*) ((uint32)f->BufStart + sizeof(uint32));

	if (index >= size) return NULL;
	return (DirectoryEntry*) &de[index];
}


/**************************************
 * INITIALIZATION ROUTINE     		  *
 **************************************/
void luxInitrdInstall (MultibootInfo* info)
{
	uint32 i;
	MountPoint* mp;

	// Register file system
	FileSystem fs = {0, "luxinitrd", luxDetect, 0, 0,
				luxOpen, luxClose, luxRead, 0, luxTest, luxReadDir};
	VfsInstallFs(&fs);

	// Check for multiboot info flags to see if any modules are loaded
	if ((info->Flags & 8) == 0) {
		Error("Initrd", "No boot modules found!");
		return;
	}

	// Loop through each module and if it is an initrd image, mount it
	MultibootModule* modules = (MultibootModule*) info->ModulesAddress;

	for (i = 0; i < info->ModulesCount; i++)
		if (*((uint32*) modules[i].ModuleStart) == LUXMAGIC)
		{
			// Mount the device
			Log("Initrd", "Found initrd image at 0x%x.\n", modules[i].ModuleStart);
			mp = VfsMount("initrd", luxInitrdDevRead, NULL, 0x0);

			// Set up data fields
			mp->FsData[0] = modules[i].ModuleStart;
			mp->FsData[1] = modules[i].ModuleEnd;
		}
		else {
			Log("Initrd", "Found module @ 0x%x, but not initrd image.\n", modules[i].ModuleStart);
		}
}