#include "lib.h"

#define DBG 0

static
ch input[32768] = {
#embed "day7_input.txt"
};

static
ch test[512] = {
#embed "day7_test.txt"
};

typedef struct { ch l[64]; } line;
static_assert(sizeof(line) == 0x40);

alignas(0x40) static
struct {
    line padstart[4];
    num file_stride;
    num stride;
    num _extra[6];
    union { line l; struct { ch s[16]; num n; }; } result;
    line padend;
} m;
static_assert(offsetof(typeof(m),result) % 64 == 0);
static_assert(offsetof(typeof(m),padend) % 64 == 0);

alignas(4096) ch buf1[256];
alignas(4096) num buf[256];

static
num do_part1(size_t file_len, ch file[file_len]) {
    m = (typeof(m)){ };
    m.result.n = 0;
#if DBG
        pnl();
#endif

    memset(buf1, 0, sizeof(buf1));

    m.file_stride = findc(file, '\n', file_len) - file;
    num linecnt = (findc(file, 0, file_len) - file) / m.file_stride;
#if DBG
    print("stride "); printd(m.file_stride); pnl();
    print("lines  "); printd(linecnt); pnl();
#endif

    num s_pos = findc(file, 'S', - 1) - 1 - file;
    buf1[s_pos] = '|';
    num line = 2;
    do {
        ch *l = file + line * m.file_stride;
        for (num col = 0; col < m.file_stride - 1; col++) {
            ch c = l[col];
            if (c == '^') {
                m.result.n += buf1[col] > 0;
                buf1[col-1] |= buf1[col];
                buf1[col+1] |= buf1[col];
                buf1[col] = 0;
            }
        }
#if DBG
        for (num col = 0; col < m.file_stride; col++) {
            if (buf1[col] == '|') print("|");
            else if (l[col] == '^') print("^");
            else print(" ");
        }
        pnl();
#endif
        line+=2;
    } while (line < linecnt);

    return m.result.n;
}

static
num do_part2(size_t file_len, ch file[file_len]) {
    m = (typeof(m)){ };
#if DBG
        pnl();
#endif

    memset(buf, 0, sizeof(buf));

    m.file_stride = findc(file, '\n', file_len) - file;
    num linecnt = (findc(file, 0, file_len) - file) / m.file_stride;
#if DBG
    print("stride "); printd(m.file_stride); pnl();
    print("lines  "); printd(linecnt); pnl();
#endif

    num s_pos = findc(file, 'S', - 1) - 1 - file;
    buf[s_pos] = 1;
    num line = 2;
    do {
        ch *l = file + line * m.file_stride;
        for (num col = 0; col < m.file_stride - 1; col++) {
            ch c = l[col];
            if (c == '^') {
                buf[col-1] += buf[col];
                buf[col+1] += buf[col];
                buf[col] = 0;
            }
        }
        for (num col = 0; col < m.file_stride; col++) {
            num v = buf[col];
#if DBG
            if (l[col] == '^') print(" ");
            else if (v >> 32) print("█");
            else if (v >> 16) print("▓");
            else if (v >>  8) print("▒");
            else if (v >>  4) print("░");
            else if (v >>  2) print("-");
            else if (v >>  0) print(".");
            else print(" ");
#endif
        }
#if DBG
        pnl();
#endif
        line+=2;
    } while (line < linecnt);

    m.result.n = 0;
    for (num col = 0; col < m.file_stride; col++) {
        m.result.n += buf[col];
    }

    return m.result.n;
}

#define RUN_TEST1 1
#define RUN_PART1 1
#define RUN_TEST2 1
#define RUN_PART2 1

#define TEST1_EXPECT 21
#define TEST2_EXPECT 40

void run() {
#if RUN_TEST1
    print("PART 1 TEST: ");
    if (num v = do_part1(countof(test), test); v != TEST1_EXPECT) {
        print("FAILED (got ");
        printd(v);
        print(", expected " xstr(TEST1_EXPECT) ")\n");
    } else {
        print("PASSED\n");
    }
#endif

#if RUN_PART1
    print("PART 1 RESULT: ");
    printd(do_part1(countof(input), input));
    print("\n");
#endif

#if RUN_TEST2
    print("PART 2 TEST: ");
    if (num v = do_part2(countof(test), test); v != TEST2_EXPECT) {
        print("FAILED (got ");
        printd(v);
        print(", expected " xstr(TEST2_EXPECT) ")\n");
    } else {
        print("PASSED\n");
    }
#endif

#if RUN_PART2
    print("PART 2 RESULT: ");
    printd(do_part2(countof(input), input));
    print("\n");
#endif

    exit_group(0);
}