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#include "shim_inflate.h"
#include "igzip_lib.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int
inflateInit2_(z_streamp strm, int windowBits)
{
        if (!strm) {
                fprintf(stderr, "Error: z_streamp is NULL\n");
                return Z_STREAM_ERROR;
        }

        struct inflate_state *isal_strm_inflate =
                (struct inflate_state *) malloc(sizeof(struct inflate_state));
        if (!isal_strm_inflate) {
                fprintf(stderr, "Error: Memory allocation for inflate_state failed\n");
                return -1;
        }

#ifdef DEBUG
        fprintf(stderr, "\nInitializing inflate with windowBits: %d", windowBits);
#endif

        /* Setup ISA-L decompression context */
        isal_inflate_init(isal_strm_inflate);

        isal_strm_inflate->avail_in = 0;
        isal_strm_inflate->next_in = NULL;
        strm->total_out = 0;
        strm->total_in = 0;

        inflate_state2 *s = (inflate_state2 *) malloc(sizeof(inflate_state2));
        if (!s) {
                free(isal_strm_inflate);
                fprintf(stderr, "Error: Memory allocation for inflate_state2 failed\n");
                return -1;
        }

        s->strm = strm;
        s->isal_strm_inflate = isal_strm_inflate;
        s->w_bits = windowBits;
        s->trailer_overconsumption_fixed = 0; // Initialize the workaround flag

        if (windowBits < 0) {
                // Raw deflate mode - no headers/trailers
                isal_strm_inflate->crc_flag = IGZIP_DEFLATE;
                isal_strm_inflate->hist_bits = -windowBits;
        } else {
                // Standard zlib format
                isal_strm_inflate->crc_flag = IGZIP_ZLIB;
                isal_strm_inflate->hist_bits = windowBits;
        }

        s->isal_strm_inflate = isal_strm_inflate;
        strm->state = (struct internal_state2 *) s;

        return Z_OK;
}

int
inflateInit_(z_streamp strm)
{
        if (!strm) {
                fprintf(stderr, "Error: z_streamp is NULL\n");
                return Z_STREAM_ERROR;
        }

        return inflateInit2_(strm, 15); // hardcoded windowBits
}

int
inflate(z_streamp strm, int flush)
{
        if (!strm) {
                fprintf(stderr, "Error: z_streamp is NULL\n");
                return Z_STREAM_ERROR;
        }

        inflate_state2 *s = (inflate_state2 *) strm->state;
        if (!s) {
                fprintf(stderr, "Error: inflate_state2 is NULL\n");
                return Z_STREAM_ERROR;
        }

        struct inflate_state *isal_strm_inflate = s->isal_strm_inflate;
        if (!isal_strm_inflate) {
                fprintf(stderr, "Error: isal_strm_inflate is NULL\n");
                return Z_STREAM_ERROR;
        }

        // set stream->avail_in, next_in, avail_out, next_out (from zstream)​
        isal_strm_inflate->next_out = strm->next_out;
        isal_strm_inflate->avail_out = strm->avail_out;
        isal_strm_inflate->avail_in = strm->avail_in;
        isal_strm_inflate->next_in = strm->next_in;
        isal_strm_inflate->total_out = strm->total_out;

#ifdef DEBUG
        fprintf(stderr, "\nInflate state: %p\n", s);
        fprintf(stderr, "Window bits: %d\n", s->w_bits);
        fprintf(stderr, "CRC flag: %d\n", isal_strm_inflate->crc_flag);
        fprintf(stderr, "Before isal_inflate: avail_in=%u, next_in=%p, avail_out=%u, next_out=%p\n",
                isal_strm_inflate->avail_in, isal_strm_inflate->next_in,
                isal_strm_inflate->avail_out, isal_strm_inflate->next_out);
        fprintf(stderr, "Total out: %u, Total_in: %lu\n", isal_strm_inflate->total_out,
                strm->total_in);
#endif

        const int decomp = isal_inflate(isal_strm_inflate);

        const unsigned int total_in = strm->total_in;
        const unsigned int original_avail_in = strm->avail_in;
        const unsigned int bytes_consumed = original_avail_in - isal_strm_inflate->avail_in;

#ifdef DEBUG
        fprintf(stderr, "After isal_inflate: avail_in=%u, next_in=%p, avail_out=%u, next_out=%p\n",
                isal_strm_inflate->avail_in, isal_strm_inflate->next_in,
                isal_strm_inflate->avail_out, isal_strm_inflate->next_out);
        fprintf(stderr, "Total out: %u, Total_in: %u\n", isal_strm_inflate->total_out,
                total_in + bytes_consumed);
        fprintf(stderr, "Bytes consumed this call: %u\n", bytes_consumed);
        fprintf(stderr, "Block state: %d (ISAL_BLOCK_FINISH=%d)\n", isal_strm_inflate->block_state,
                ISAL_BLOCK_FINISH);
        fprintf(stderr, "Flush: %d, ISA-L result: %d\n", flush, decomp);

        if (isal_strm_inflate->block_state == ISAL_BLOCK_FINISH &&
            isal_strm_inflate->avail_in > 0) {
                fprintf(stderr, "WARNING: BLOCK_FINISH reached but %u bytes remain in input:\n",
                        isal_strm_inflate->avail_in);
                for (unsigned int i = 0; i < isal_strm_inflate->avail_in && i < 16; i++) {
                        fprintf(stderr, " %02x", ((unsigned char *) isal_strm_inflate->next_in)[i]);
                }
                fprintf(stderr, "\n");
        }
#endif

        // WORKAROUND: ISA-L over-consumption fix for raw deflate mode
        if ((isal_strm_inflate->block_state == ISAL_BLOCK_FINISH ||
             isal_strm_inflate->block_state == ISAL_BLOCK_INPUT_DONE) &&
            (isal_strm_inflate->crc_flag == 0) &&    // raw deflate
            s->trailer_overconsumption_fixed == 0 && // hasn't been applied yet
            decomp == ISAL_DECOMP_OK &&              // successful decompression
            isal_strm_inflate->avail_in < 8 && isal_strm_inflate->avail_in > 0) {

                // Calculate how many bytes were likely over-consumed
                const unsigned int expected_trailer_bytes = 8;
                const unsigned int over_consumed =
                        expected_trailer_bytes - isal_strm_inflate->avail_in;

                // Only apply fix if the over-consumption is reasonable (1-7 bytes)
                if (over_consumed >= 1 && over_consumed <= 7) {
#ifdef DEBUG
                        fprintf(stderr,
                                "APPLYING WORKAROUND: Detected ISA-L over-consumption of %u "
                                "bytes\n",
                                over_consumed);
                        fprintf(stderr, "Adjusting next_in from %p to %p, avail_in from %u to %u\n",
                                isal_strm_inflate->next_in,
                                (unsigned char *) isal_strm_inflate->next_in - over_consumed,
                                isal_strm_inflate->avail_in,
                                isal_strm_inflate->avail_in + over_consumed);
#endif
                        // Rewind the input pointer to restore over-consumed bytes
                        isal_strm_inflate->next_in =
                                (unsigned char *) isal_strm_inflate->next_in - over_consumed;
                        isal_strm_inflate->avail_in += over_consumed;

                        // Mark that the workaround has been applied
                        s->trailer_overconsumption_fixed = 1;

                        // Also adjust the byte consumption count to reflect the actual deflate data
                        // consumed Note: bytes_consumed is calculated later, so we'll need to
                        // adjust it after the calculation
                }
        }

        // Update stream state - handle byte accounting correctly
        strm->avail_out = isal_strm_inflate->avail_out;
        strm->avail_in = isal_strm_inflate->avail_in;
        strm->next_in = isal_strm_inflate->next_in;
        strm->next_out = isal_strm_inflate->next_out;
        strm->total_out = isal_strm_inflate->total_out;

        // Calculate bytes consumed by ISA-L from the original input
        const unsigned int bytes_consumed_by_isal = original_avail_in - isal_strm_inflate->avail_in;
        strm->total_in = total_in + bytes_consumed_by_isal;

        int ret;

        if (decomp == ISAL_DECOMP_OK) {
                if (isal_strm_inflate->block_state == ISAL_BLOCK_FINISH) {
                        // ISA-L has finished processing the deflate stream including trailer
                        // validation
                        ret = Z_STREAM_END;
                        strm->msg = "ok";
                } else {
                        // Still processing, continue
                        ret = Z_OK;
                }
        } else if (decomp == ISAL_END_INPUT) {
                ret = Z_OK;
        } else {
                ret = Z_DATA_ERROR;
        }

#ifdef DEBUG
        if (ret == Z_OK) {
                fprintf(stderr, "Inflate finished successfully Z_OK\n");
        } else if (ret == Z_STREAM_END) {
                fprintf(stderr, "Inflate finished with Z_STREAM_END\n");
        } else {
                fprintf(stderr, "Inflate finished with error code: %d\n", ret);
                switch (decomp) {
                case ISAL_INVALID_BLOCK:
                        fprintf(stderr, "Error: ISA-L error - Invalid block\n");
                        break;
                case ISAL_INVALID_SYMBOL:
                        fprintf(stderr, "Error: ISA-L error - Invalid symbol\n");
                        break;
                case ISAL_INVALID_LOOKBACK:
                        fprintf(stderr, "Error: ISA-L error - Invalid lookback\n");
                        break;
                case ISAL_END_INPUT:
                        fprintf(stderr, "Error: ISA-L error - End of input reached unexpectedly\n");
                        break;
                case ISAL_UNSUPPORTED_METHOD:
                        fprintf(stderr, "Error: ISA-L error - Unsupported method\n");
                        break;
                case ISAL_NEED_DICT:
                        fprintf(stderr, "Error: ISA-L error - Need dictionary\n");
                        break;
                default:
                        fprintf(stderr, "Error: ISA-L error code: %d\n", decomp);
                        break;
                }
        }
#endif

        return ret;
}

int
inflateEnd(z_streamp strm)
{
        if (!strm) {
                fprintf(stderr, "Error: z_streamp is NULL\n");
                return Z_STREAM_ERROR;
        }

        inflate_state2 *s = (inflate_state2 *) strm->state;
        if (s) {
                free(s->isal_strm_inflate);
                free(s);
        }

        strm->state = NULL;

#ifdef DEBUG
        fprintf(stderr, "Inflate end\n");
#endif
        return Z_OK;
}

int
inflateSetDictionary(z_streamp strm, unsigned char *dict_data, unsigned int dict_len)
{
        if (!strm || !strm->state || !dict_data || dict_len == 0)
                return Z_STREAM_ERROR;

        const inflate_state2 *s = (inflate_state2 *) strm->state;

        if (!s || !s->isal_strm_inflate)
                return Z_STREAM_ERROR;

        return isal_inflate_set_dict(s->isal_strm_inflate, dict_data, dict_len);
}

int
uncompress2(uint8_t *dest, unsigned long *dest_len, const uint8_t *source,
            unsigned long *source_len)
{
        z_stream strm;
        int err;
        const unsigned int max = (unsigned int) -1;
        unsigned long len, left;
        uint8_t buf[1] = { 0 }; /* for detection of incomplete strm when *dest_len == 0 */

        len = *source_len;
        if (*dest_len) {
                left = *dest_len;
                *dest_len = 0;
        } else {
                left = 1;
                dest = buf;
        }

        strm.next_in = (uint8_t *) source;
        strm.avail_in = 0;
        strm.zalloc = NULL;
        strm.zfree = NULL;
        strm.opaque = NULL;

        err = inflateInit_(&strm);
        if (err != Z_OK)
                return err;

        strm.next_out = dest;
        strm.avail_out = 0;

        do {
                if (strm.avail_out == 0) {
                        strm.avail_out = left > (unsigned long) max ? max : (unsigned int) left;
                        left -= strm.avail_out;
                }
                if (strm.avail_in == 0) {
                        strm.avail_in = len > (unsigned long) max ? max : (unsigned int) len;
                        len -= strm.avail_in;
                }
                err = inflate(&strm, Z_NO_FLUSH);
        } while (err == Z_OK);

        *source_len -= len + strm.avail_in;
        if (dest != buf)
                *dest_len = strm.total_out;
        else if (strm.total_out && err == Z_BUF_ERROR)
                left = 1;

        inflateEnd(&strm);
        return err == Z_STREAM_END                           ? Z_OK
               : err == Z_NEED_DICT                          ? Z_DATA_ERROR
               : err == Z_BUF_ERROR && left + strm.avail_out ? Z_DATA_ERROR
                                                             : err;
}

int
uncompress(uint8_t *dest, unsigned long *dest_len, const uint8_t *source, unsigned long source_len)
{
        return uncompress2(dest, dest_len, source, &source_len);
}

int
inflateReset(z_streamp strm)
{
        if (!strm) {
                fprintf(stderr, "Error: z_streamp is NULL\n");
                return Z_STREAM_ERROR;
        }

        inflate_state2 *s = (inflate_state2 *) strm->state;
        if (!s) {
                fprintf(stderr, "Error: inflate_state2 is NULL\n");
                return Z_STREAM_ERROR;
        }

        struct inflate_state *isal_strm_inflate = s->isal_strm_inflate;
        if (!isal_strm_inflate) {
                fprintf(stderr, "Error: isal_strm_inflate is NULL\n");
                return Z_STREAM_ERROR;
        }

        // Reset ISA-L inflate state
        isal_inflate_reset(isal_strm_inflate);

        strm->total_out = 0;
        strm->total_in = 0;
        strm->msg = NULL;

        // Reset workaround flag
        s->trailer_overconsumption_fixed = 0;

        return Z_OK;
}