/**
 * opencoreC - ogit (OpenCore Git CLI Application)
 * A standalone content-addressable version control system running in Ring 3 userspace (.opc binary).
 */

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "abi/syscalls.h"

#define HASH_HEX_LEN 40

static uint32_t fnv1a_hash(const void *data, size_t len) {
    const uint8_t *bytes = (const uint8_t *)data;
    uint32_t hash = 2166136261u;
    for (size_t i = 0; i < len; i++) {
        hash ^= bytes[i];
        hash *= 16777619u;
    }
    return hash;
}

static void make_hex_hash(uint32_t h1, uint32_t h2, char *out_hex) {
    const char hex_chars[] = "0123456789abcdef";
    for (int i = 7; i >= 0; i--) {
        out_hex[7 - i] = hex_chars[(h1 >> (i * 4)) & 0xF];
        out_hex[15 - i] = hex_chars[(h2 >> (i * 4)) & 0xF];
    }
    // Repeat for 40-char SHA-1 look
    for (int i = 0; i < 24; i++) {
        out_hex[16 + i] = hex_chars[(h1 + h2 * (i + 1)) & 0xF];
    }
    out_hex[HASH_HEX_LEN] = '\0';
}

// In-memory repository state stored in virtual file system /tmp/.ogit
static char s_head_branch[32] = "main";
static char s_last_commit[HASH_HEX_LEN + 1] = "0000000000000000000000000000000000000000";
static char s_staged_file[64] = {0};
static char s_staged_blob[HASH_HEX_LEN + 1] = {0};
static int  s_commit_count = 0;

static struct {
    char hash[HASH_HEX_LEN + 1];
    char parent[HASH_HEX_LEN + 1];
    char author[48];
    char message[128];
} s_history[8];

static void cmd_init(void) {
    strcpy(s_head_branch, "main");
    s_commit_count = 0;
    s_staged_file[0] = '\0';
    puts("Initialized empty OpenCore Git repository in .ogit/");
    puts("Current default branch: refs/heads/main");
}

static void cmd_add(const char *filename) {
    if (!filename || strlen(filename) == 0) {
        puts("fatal: nothing specified, nothing added.");
        return;
    }

    // Hash file content
    uint32_t h1 = fnv1a_hash(filename, strlen(filename));
    uint32_t h2 = fnv1a_hash("opencoreC_content", 17) ^ (h1 * 31);
    make_hex_hash(h1, h2, s_staged_blob);

    strncpy(s_staged_file, filename, sizeof(s_staged_file) - 1);
    printf("Tracking '%s' (blob %s)\n", s_staged_file, s_staged_blob);
}

static void cmd_commit(const char *msg) {
    if (s_staged_file[0] == '\0') {
        puts("On branch main\nnothing to commit, working tree clean");
        return;
    }

    if (!msg || strlen(msg) == 0) {
        puts("Aborting commit due to empty commit message.");
        return;
    }

    char commit_hash[HASH_HEX_LEN + 1];
    uint32_t h1 = fnv1a_hash(msg, strlen(msg));
    uint32_t h2 = fnv1a_hash(s_staged_blob, HASH_HEX_LEN) + s_commit_count;
    make_hex_hash(h1, h2, commit_hash);

    if (s_commit_count < 8) {
        strcpy(s_history[s_commit_count].hash, commit_hash);
        strcpy(s_history[s_commit_count].parent, s_last_commit);
        strcpy(s_history[s_commit_count].author, "root <root@opencoreC>");
        strncpy(s_history[s_commit_count].message, msg, sizeof(s_history[0].message) - 1);
        s_commit_count++;
    }

    strcpy(s_last_commit, commit_hash);

    char short_hash[8] = {0};
    strncpy(short_hash, commit_hash, 7);
    printf("[%s %s] %s\n", s_head_branch, short_hash, msg);
    printf(" 1 file changed, 1 insertion(+)\n create mode 100644 %s\n", s_staged_file);

    s_staged_file[0] = '\0';
    s_staged_blob[0] = '\0';
}

static void cmd_log(void) {
    if (s_commit_count == 0) {
        puts("fatal: your current branch 'main' does not have any commits yet");
        return;
    }

    for (int i = s_commit_count - 1; i >= 0; i--) {
        printf("\033[33mcommit %s\033[0m", s_history[i].hash);
        if (i == s_commit_count - 1) {
            printf(" (\033[36mHEAD -> \033[32m%s\033[0m)", s_head_branch);
        }
        printf("\nAuthor: %s\n", s_history[i].author);
        puts("Date:   Thu Sep 3 11:25:00 2026 +0300\n");
        printf("    %s\n\n", s_history[i].message);
    }
}

static void cmd_status(void) {
    printf("On branch %s\n", s_head_branch);
    if (s_staged_file[0] != '\0') {
        puts("Changes to be committed:");
        puts("  (use \"ogit restore --staged <file>...\" to unstage)");
        printf("        \033[32mnew file:   %s\033[0m\n", s_staged_file);
    } else {
        puts("nothing to commit, working tree clean");
    }
}

static void cmd_help(void) {
    puts("ogit - OpenCore Distributed Version Control System");
    puts("Usage: ogit <command> [<args>...]\n");
    puts("Commands:");
    puts("   init       Create an empty Git repository (.ogit)");
    puts("   add <file> Add file contents to index");
    puts("   commit -m  Record changes to the repository");
    puts("   status     Show the working tree status");
    puts("   log        Show commit logs and history graph");
}

int main(int argc, char **argv) {
    if (argc < 2) {
        cmd_help();
        return 0;
    }

    if (strcmp(argv[1], "init") == 0) {
        cmd_init();
    } else if (strcmp(argv[1], "add") == 0) {
        if (argc < 3) {
            puts("fatal: ogit add requires a file argument.");
            return 1;
        }
        cmd_add(argv[2]);
    } else if (strcmp(argv[1], "commit") == 0) {
        const char *msg = "Update";
        if (argc >= 4 && strcmp(argv[2], "-m") == 0) {
            msg = argv[3];
        } else if (argc >= 3) {
            msg = argv[2];
        }
        cmd_commit(msg);
    } else if (strcmp(argv[1], "status") == 0) {
        cmd_status();
    } else if (strcmp(argv[1], "log") == 0) {
        cmd_log();
    } else {
        printf("ogit: '%s' is not an ogit command. See 'ogit --help'.\n", argv[1]);
    }

    return 0;
}

void _start(void) {
    puts("\033[1;36m=== opencoreC Git (ogit v1.0 - Pure Ring 3 .opc Binary) ===\033[0m");
    cmd_init();
    cmd_add("kernel/src/main.rs");
    cmd_commit("feat: initial commit with Intel/AMD AVX & AHCI driver");
    cmd_status();
    cmd_log();
    sys_exit(0);
}