#include "devil1tex.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

void printtph (struct TexturePack *tp) {
    if (tp != NULL) { 
        printf("id: \t %c %c %c %c \n", tp -> id[3], 
                                        tp -> id[2], 
                                        tp -> id[1], 
                                        tp -> id[0]);
        printf("batch#: \t %i \n",    tp -> batchNumber);
        printf("1st batch: \t %i \n", tp -> firstBatchOffset);
        printf("unknownA: \t %i\n",   tp -> unknownA);
    }
    return;
}

void printtbd(struct TextureBatchDescriptor *bd) {
    if (bd != NULL) {
        printf("batch index: \t %i \n", bd -> batchIdx);
        printf("hash: \t %u \n",        bd -> hash);
        printf("textures: \t %i\n",     bd -> texNumber);
    }
}

// get texture pack descriptors
void gettbd (struct TextureBatchDescriptor **descriptors,
             const char *filedata,
             unsigned int filesize) {
    if (descriptors == NULL || filedata == NULL || filesize <= 0) {
        return;
    }
    struct TexturePack *tp = NULL;
    tp = (struct TexturePack*)filedata;
    if (filesize <= (sizeof(struct TextureBatchDescriptor) 
                    * tp -> batchNumber 
                    + sizeof(struct TexturePack))){
        fprintf(stderr, 
                "File Error: file size to struct sizes ratio.\n");
        return;
    }
    unsigned int index = sizeof(struct TexturePack);
    // Batch Descriptors are structured one after another.
    // therefore the next one is at
    // current index + sizeof(TextureBatchDescriptor)
    unsigned int i = 0;
    do {
        index = sizeof(struct TextureBatchDescriptor) * i 
                + sizeof(struct TexturePack);
        printf("batch descriptor start: %x\n", index);
        descriptors[i] = (struct TextureBatchDescriptor*)
                            (filedata + index);
        i++;
    } while(i < (tp -> batchNumber));
    return;
}

// returns total count of textures in the file.
unsigned int gettexturebatch(
                     struct TextureBatch **tb,
                     struct TextureBatchDescriptor **bds,
                     const char *filedata, 
                     unsigned int filesize) {
    struct TexturePack *tp              = (struct TexturePack*)filedata;
    unsigned int offset = tp -> firstBatchOffset;
    unsigned int i;
    unsigned int j;
    unsigned int totaltextures = 0;
    // TextureBatch shares a starting address with the first texture
    // and shares the ending address with the last texture.
    for (i = 0; i < tp -> batchNumber; i++) {
        tb[i] = (struct TextureBatch*)filedata + offset;
        // the next texture batch is TextureSize * number of textures away.
        offset        += bds[i] -> textureSize * (bds[i] -> texNumber);
        totaltextures += bds[i] -> texNumber;
    }
    return totaltextures;
}
 
void locatetextures(unsigned int *t,
                    struct TexturePack *tp,
                    struct TextureBatchDescriptor **bds) {
    unsigned int i;
    unsigned int j;
    // k is access to index of textures.
    unsigned int k = 0;
    unsigned int offset = tp -> firstBatchOffset;
    for (i = 0; i < tp -> batchNumber; i++) {
        for (j = 0; j < bds[i] -> texNumber; j++) {
            t[k]    = offset;
            offset += bds[i] -> textureSize;
            k++;
        }
    }
}
// -------------------------------------------------------+
//                  Revision Functions
// -------------------------------------------------------+

// ** = 'pass by reference' of a pointer to struct
bool gettexdescriptor(struct TextureBatchDescriptor **descriptor,
                      unsigned int i,
                      const char *filedata,
                      unsigned int filesize) {
    // starts after the pack header.
    bool done = false;
    unsigned int offset = sizeof(struct TexturePack);
    offset += sizeof(struct TextureBatchDescriptor) * i;
    if (filedata != NULL) {
        *descriptor = (struct TextureBatchDescriptor*)(filedata + offset);
        done = true;
    }
//    printf("%x %x", *descriptor, filedata);
    return done;
}

// ** = 'pass by reference' of a pointer to struct
bool gettexbatch(struct TextureBatch **batch, 
                 unsigned int i, 
                 const char *filedata,
                 unsigned int filesize) {
    struct TexturePack *p = NULL;
    if (filedata == NULL) {      // no data to get batch from.
        return false;
    }
    p = (struct TexturePack*)filedata;
    if (i > p -> batchNumber) {  // no such batch in texture pack
        return false;
    }
    if (i == 0) {
        *batch = (struct TextureBatch*)(filedata + (p -> firstBatchOffset));
        return true;
    }
    struct TextureBatchDescriptor *d = NULL;
    // find how large are previous batches in total
    // in order to jump to specified texture batch
    unsigned int pastbatchsize = p -> firstBatchOffset;
    unsigned int j;
    for (j = 0; j < i; j++) {
        gettexdescriptor(&d, j, filedata, filesize);
        pastbatchsize += (d -> textureSize * d -> texNumber);
    }
    *batch = (struct TextureBatch*)(filedata + pastbatchsize);
    //printf("batch offset: %x i: %d\n" , (p -> firstBatchOffset) + pastbatchsize, i);
    return true;
}

bool unpacktexbatch(struct Texture *t,
                    unsigned int i,
                    const char *filedata, 
                    const unsigned int filesize) {
    if (filedata == NULL) {
        return false;
    }
    struct TextureBatch *b           = NULL;
    struct TextureBatchDescriptor *d = NULL;
    gettexbatch(&b, i, filedata, filesize);
    gettexdescriptor(&d, i, filedata, filesize);

    // first texture is at the start of the batch
    // second texture is right after.
    unsigned int j;
    for (j = 0; j < d -> texNumber; j++) {
        t[j].data = (unsigned char*)b + (d -> textureSize * j);
        //printf("unpack relative batch offset %x  i= %i t.data= %x\n" , ((d -> textureSize * j)), i, t[j].data);
    }
    return true;
}