#include "gpusolver.h"
#include <CL/cl.h>
#include "time.h"

#define GLOBAL_SIZE (256)
#define LOCAL_SIZE (GLOBAL_SIZE)

#define CHECKASGN (true)

#define DEBUG

i32 gpusolve(cnf* c) {
    cl_platform_id platformid = NULL;
    cl_device_id deviceid = NULL;
    cl_uint numdevices;
    cl_uint numplatforms;

    FILE *fp;
    char *source_str;
    size_t source_size;

    fp = fopen("../psat.cl", "r");
    if (!fp) {
        fprintf(stderr, "Failed to load kernel.\n");
        exit(1);
    }
    source_str = (char*)malloc(0x100000);
    source_size = fread( source_str, 1, 0x100000, fp);
    fclose( fp );

    u32 wordcnt = 1 + ((c->varcnt) >> 5U);

    u32* solution = calloc((wordcnt + 1), sizeof(u32));
    if (solution == NULL) {
        printf("Failed to allocate solution buffer\n");
        exit(1);
    }

    cl_int res = clGetPlatformIDs(1, &platformid, &numplatforms);
    if (res != CL_SUCCESS) {
        printf("Failed to retrieve OpenCL platform IDs\n");
        exit(1);
    }
    // printf("Found %u platforms\n", numplatforms);
    res = clGetDeviceIDs(platformid, CL_DEVICE_TYPE_GPU, 1, &deviceid, &numdevices);
    if (res != CL_SUCCESS) {
        printf("Failed to retrieve OpenCL device IDs\n");
        exit(1);
    }
    // printf("Found %u devices\n", numdevices);

    cl_context context = clCreateContext(NULL, 1, &deviceid, NULL, NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create OpenCL context\n");
        exit(1);
    }

    cl_command_queue commqueue = clCreateCommandQueueWithProperties(context, deviceid, 0, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create OpenCL command queue\n");
        exit(1);
    }

    // Device memory buffers:
    /* For the CNF:
     * {clausecnt, literalcnt, varcnt)
     * variable array
     * clause array
     * parity array
     *
     * Other:
     * Status
     * A single counter
     */

    // TODO: Look into DMA, maybe? Could do clause learning CPU-side and just update the GPU buffer
    cl_mem gpuheader = clCreateBuffer(context, CL_MEM_READ_ONLY, 3 * sizeof(cl_uint), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF header buffer\n");
        exit(1);
    }
    cl_mem gpulvars = clCreateBuffer(context, CL_MEM_READ_ONLY, c->clausecnt * sizeof(cl_uint), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF lvar buffer\n");
        exit(1);
    }
    cl_mem gpuvariables = clCreateBuffer(context, CL_MEM_READ_ONLY, c->litcnt * sizeof(cl_uint), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF variable buffer\n");
        exit(1);
    }
    cl_mem gpuclauses = clCreateBuffer(context, CL_MEM_READ_ONLY, c->litcnt * sizeof(cl_uint), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF clause buffer\n");
        exit(1);
    }
    cl_mem gpuparities = clCreateBuffer(context, CL_MEM_READ_ONLY, c->litcnt * sizeof(cl_uchar), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF parity buffer\n");
        exit(1);
    }

    // Allocate scratchpad memory
    cl_mem gpuscratchpad = clCreateBuffer(context, CL_MEM_READ_WRITE, c->clausecnt * sizeof(cl_uchar), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF subsumption scratchpad buffer\n");
        exit(1);
    }
    /*
    cl_mem gpumaxvals = clCreateBuffer(context, CL_MEM_READ_WRITE, GLOBAL_SIZE * sizeof(cl_uint), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create CNF maxval buffer\n");
        exit(1);
    }
     */

    cl_mem gpuoutput = clCreateBuffer(context, CL_MEM_READ_WRITE, (wordcnt + 1) * sizeof(cl_uint), NULL, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create output buffer\n");
        exit(1);
    }

    u32 cnfheader[3] = { c->litcnt, c->varcnt, c->clausecnt };

    // Load buffers to GPU
    res = clEnqueueWriteBuffer(commqueue, gpuheader, CL_TRUE, 0, 3 * sizeof(cl_uint), cnfheader, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to queue CNF header write\n");
        exit(1);
    }
    res = clEnqueueWriteBuffer(commqueue, gpulvars, CL_TRUE, 0, c->clausecnt * sizeof(cl_uint), c->lastvars, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to queue CNF lvar write\n");
        exit(1);
    }
    res = clEnqueueWriteBuffer(commqueue, gpuvariables, CL_TRUE, 0, c->litcnt * sizeof(cl_uint), c->variables, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to queue CNF variable write\n");
        exit(1);
    }
    res = clEnqueueWriteBuffer(commqueue, gpuclauses, CL_TRUE, 0, c->litcnt * sizeof(cl_uint), c->clauses, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to queue CNF clause write\n");
        exit(1);
    }
    res = clEnqueueWriteBuffer(commqueue, gpuparities, CL_TRUE, 0, c->litcnt * sizeof(cl_uchar), c->pars, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to queue CNF parity write\n");
        exit(1);
    }

    cl_program satprog = clCreateProgramWithSource(context, 1, (const char**) &source_str, (const size_t*) &source_size, &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create OpenCL program\n");
        exit(1);
    }

    res = clBuildProgram(satprog, 1, &deviceid, NULL, NULL, NULL);
    if (res != CL_SUCCESS) {
        char* logbuf = malloc(sizeof(char) * 65536);
        size_t loglen = 0;
        res = clGetProgramBuildInfo(satprog, deviceid, CL_PROGRAM_BUILD_LOG, sizeof(char) * 65536, logbuf, &loglen);
        if (res != CL_SUCCESS) {
            printf("Failed to retrieve build logs\n");
            exit(1);
        }
        printf("Build failed\n");
        printf("%s\n", logbuf);
        free(logbuf);
        exit(1);
    }

    cl_kernel kernel = clCreateKernel(satprog, "vectorSAT", &res);
    if (res != CL_SUCCESS) {
        printf("Failed to create kernel\n");
        exit(1);
    }

    res = clSetKernelArg(kernel, 0, sizeof(cl_mem), (void*) &gpuheader);
    res = clSetKernelArg(kernel, 1, sizeof(cl_mem), (void*) &gpulvars);
    res = clSetKernelArg(kernel, 2, sizeof(cl_mem), (void*) &gpuvariables);
    res = clSetKernelArg(kernel, 3, sizeof(cl_mem), (void*) &gpuclauses);
    res = clSetKernelArg(kernel, 4, sizeof(cl_mem), (void*) &gpuparities);

    res = clSetKernelArg(kernel, 5, sizeof(cl_mem), (void*) &gpuoutput);

    res = clSetKernelArg(kernel, 6, sizeof(cl_mem), (void*) &gpuscratchpad);
    res = clSetKernelArg(kernel, 7, LOCAL_SIZE * sizeof(cl_uint), NULL);

    // u64 starttime = utime();
    size_t itemsize[2] = {GLOBAL_SIZE, LOCAL_SIZE };
    res = clEnqueueNDRangeKernel(commqueue, kernel, 1, NULL, itemsize, itemsize + 1, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to queue kernel for execution\n");
        exit(res);
    }

    res = clEnqueueReadBuffer(commqueue, gpuoutput, CL_TRUE, 0, (wordcnt + 1) * sizeof(cl_uint), solution, 0, NULL, NULL);
    if (res != CL_SUCCESS) {
        printf("Failed to read kernel output\n");
        exit(1);
    }
    // u64 endtime = utime();

    if (solution[0] == 1) {
        printf("UNSAT\n");
    } else if (solution[0] == 0) {
        printf("SAT\n");
        for (u32 k = 0; k < c->varcnt; ++k) {
            u32 vind = (c->varcnt - 1) - k;
            u32 iind = vind >> 5U;
            u32 bind = vind & 0b11111U;
            u8 par = (solution[iind + 1] >> bind) & 1U;
            printf("%u", par);
        }
        printf("\n");
        if (CHECKASGN) {
            u8* assigncheck = calloc(c->clausecnt, sizeof(u8));
            for (u32 i = 0; i < c->litcnt; ++i) {
                u32 g = ((c->varcnt - 1) - c->variables[i]) >> 5U;
                u32 h = ((c->varcnt - 1) - c->variables[i]) & 0b11111U;
                u8 paract = (solution[g + 1] >> h) & 1U;
                if (c->pars[i] == paract) assigncheck[c->clauses[i]] = true;
            }
            for (u32 i = 0; i < c->clausecnt; ++i) {
                if (!assigncheck[i]) {
                    printf("Failed assignment check\n");
                    solution[0] = 4;
                }
            }
            free(assigncheck);
            printf("Passed assignment check\n");
        }
    } else {
        printf("What the fuck???\n");
        solution[0] = 3;
    }
    // printf("Actual time: %f seconds\n", ((f64) (endtime - starttime)) / 1000000.0);

    res = clFlush(commqueue);
    res = clFinish(commqueue);
    res = clReleaseKernel(kernel);
    res = clReleaseProgram(satprog);

    res = clReleaseCommandQueue(commqueue);
    res = clReleaseContext(context);

    res = clReleaseMemObject(gpuheader);
    res = clReleaseMemObject(gpulvars);
    res = clReleaseMemObject(gpuvariables);
    res = clReleaseMemObject(gpuclauses);
    res = clReleaseMemObject(gpuparities);
    res = clReleaseMemObject(gpuoutput);
    res = clReleaseMemObject(gpuscratchpad);

    res = clReleaseDevice(deviceid);

    i32 retval = solution[0];
    free(solution);
    free(source_str);

    return retval;
}