/* mp_auth.c — 访问级 PIN 鉴权（panel.pin）+ 内联 SHA-256 + 内存会话。 */
#include "mp.h"

time_t g_auth_ttl = AUTH_TOKEN_TTL;
#define PIN_MAX_FAILS      5              /* 连续错 PIN 锁定阈值 */
#define PIN_LOCK_SEC       300            /* 锁定 5 分钟 */
static const uint32_t mp_sha256_k[64] = {
    0x428a2f98u,0x71374491u,0xb5c0fbcfu,0xe9b5dba5u,0x3956c25bu,0x59f111f1u,0x923f82a4u,0xab1c5ed5u,
    0xd807aa98u,0x12835b01u,0x243185beu,0x550c7dc3u,0x72be5d74u,0x80deb1feu,0x9bdc06a7u,0xc19bf174u,
    0xe49b69c1u,0xefbe4786u,0x0fc19dc6u,0x240ca1ccu,0x2de92c6fu,0x4a7484aau,0x5cb0a9dcu,0x76f988dau,
    0x983e5152u,0xa831c66du,0xb00327c8u,0xbf597fc7u,0xc6e00bf3u,0xd5a79147u,0x06ca6351u,0x14292967u,
    0x27b70a85u,0x2e1b2138u,0x4d2c6dfcu,0x53380d13u,0x650a7354u,0x766a0abbu,0x81c2c92eu,0x92722c85u,
    0xa2bfe8a1u,0xa81a664bu,0xc24b8b70u,0xc76c51a3u,0xd192e819u,0xd6990624u,0xf40e3585u,0x106aa070u,
    0x19a4c116u,0x1e376c08u,0x2748774cu,0x34b0bcb5u,0x391c0cb3u,0x4ed8aa4au,0x5b9cca4fu,0x682e6ff3u,
    0x748f82eeu,0x78a5636fu,0x84c87814u,0x8cc70208u,0x90befffau,0xa4506cebu,0xbef9a3f7u,0xc67178f2u
};
static int    g_pin_fails = 0;
static time_t g_pin_locked_until = 0;
static auth_sess_t g_sess[AUTH_MAX_SESS];
static int g_sess_n = 0;
#define MP_ROR(x,n)  (((x) >> (n)) | ((x) << (32 - (n))))
#define MP_CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
#define MP_MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define MP_BSIG0(x)  (MP_ROR(x,2) ^ MP_ROR(x,13) ^ MP_ROR(x,22))
#define MP_BSIG1(x)  (MP_ROR(x,6) ^ MP_ROR(x,11) ^ MP_ROR(x,25))
#define MP_SSIG0(x)  (MP_ROR(x,7) ^ MP_ROR(x,18) ^ ((x) >> 3))
#define MP_SSIG1(x)  (MP_ROR(x,17) ^ MP_ROR(x,19) ^ ((x) >> 10))


void mp_sha256_init(mp_sha256_ctx *c)
{
    c->state[0] = 0x6a09e667u; c->state[1] = 0xbb67ae85u;
    c->state[2] = 0x3c6ef372u; c->state[3] = 0xa54ff53au;
    c->state[4] = 0x510e527fu; c->state[5] = 0x9b05688cu;
    c->state[6] = 0x1f83d9abu; c->state[7] = 0x5be0cd19u;
    c->count = 0; c->buflen = 0;
}

void mp_sha256_block(mp_sha256_ctx *c, const uint8_t *p)
{
    uint32_t w[64];
    int i;
    for (i = 0; i < 16; i++)
        w[i] = ((uint32_t)p[i*4] << 24) | ((uint32_t)p[i*4+1] << 16) |
               ((uint32_t)p[i*4+2] << 8)  |  (uint32_t)p[i*4+3];
    for (i = 16; i < 64; i++)
        w[i] = MP_SSIG1(w[i-2]) + w[i-7] + MP_SSIG0(w[i-15]) + w[i-16];
    uint32_t a = c->state[0], b = c->state[1], cc = c->state[2], d = c->state[3];
    uint32_t e = c->state[4], f = c->state[5], g = c->state[6], h = c->state[7];
    for (i = 0; i < 64; i++) {
        uint32_t t1 = h + MP_BSIG1(e) + MP_CH(e,f,g) + mp_sha256_k[i] + w[i];
        uint32_t t2 = MP_BSIG0(a) + MP_MAJ(a,b,cc);
        h = g; g = f; f = e; e = d + t1;
        d = cc; cc = b; b = a; a = t1 + t2;
    }
    c->state[0] += a; c->state[1] += b; c->state[2] += cc; c->state[3] += d;
    c->state[4] += e; c->state[5] += f; c->state[6] += g; c->state[7] += h;
}

void mp_sha256_update(mp_sha256_ctx *c, const uint8_t *data, size_t len)
{
    c->count += (uint64_t)len;
    if (c->buflen) {
        size_t need = 64 - c->buflen;
        size_t take = len < need ? len : need;
        memcpy(c->buf + c->buflen, data, take);
        c->buflen += take; data += take; len -= take;
        if (c->buflen == 64) { mp_sha256_block(c, c->buf); c->buflen = 0; }
    }
    while (len >= 64) { mp_sha256_block(c, data); data += 64; len -= 64; }
    if (len) { memcpy(c->buf, data, len); c->buflen = len; }
}

void mp_sha256_final(mp_sha256_ctx *c, uint8_t out[32])
{
    uint64_t bitlen = c->count * 8;
    uint8_t *b = c->buf;
    size_t bl = c->buflen;
    int i;
    b[bl++] = 0x80;
    if (bl > 56) {
        while (bl < 64) b[bl++] = 0;
        mp_sha256_block(c, b);
        bl = 0;
    }
    while (bl < 56) b[bl++] = 0;
    for (i = 0; i < 8; i++)
        b[bl++] = (uint8_t)(bitlen >> (56 - i * 8));
    mp_sha256_block(c, b);
    for (i = 0; i < 8; i++) {
        out[i*4]   = (uint8_t)(c->state[i] >> 24);
        out[i*4+1] = (uint8_t)(c->state[i] >> 16);
        out[i*4+2] = (uint8_t)(c->state[i] >> 8);
        out[i*4+3] = (uint8_t)(c->state[i]);
    }
}

int auth_read_random(unsigned char *buf, size_t n)
{
    int fd = open("/dev/urandom", O_RDONLY);
    if (fd < 0) return -1;
    size_t got = 0;
    while (got < n) {
        ssize_t rd = read(fd, buf + got, n - got);
        if (rd <= 0) { close(fd); return -1; }
        got += (size_t)rd;
    }
    close(fd);
    return 0;
}

void auth_hex(const unsigned char *raw, size_t n, char *out)
{
    static const char hex[] = "0123456789abcdef";
    for (size_t i = 0; i < n; i++) {
        out[i*2]   = hex[raw[i] >> 4];
        out[i*2+1] = hex[raw[i] & 0xf];
    }
    out[n*2] = 0;
}

int auth_token_gen(char *out, int outcap)       /* 16B → 32 hex（128bit） */
{
    unsigned char raw[AUTH_TOKEN_BYTES];
    if (outcap < AUTH_TOKEN_BYTES * 2 + 1) return -1;
    if (auth_read_random(raw, sizeof raw) < 0) return -1;
    auth_hex(raw, sizeof raw, out);
    return 0;
}

int auth_make_salt(char *out, int outcap)        /* 16B → 32 hex 盐 */
{
    unsigned char raw[16];
    if (outcap < 33) return -1;
    if (auth_read_random(raw, sizeof raw) < 0) return -1;
    auth_hex(raw, sizeof raw, out);
    return 0;
}

int auth_pass_hash(const char *salt, const char *password, char *out, int outcap)
{
    mp_sha256_ctx c;
    uint8_t digest[32];
    if (outcap < AUTH_HASH_LEN + 1) return -1;
    mp_sha256_init(&c);
    mp_sha256_update(&c, (const uint8_t *)salt, strlen(salt));
    mp_sha256_update(&c, (const uint8_t *)password, strlen(password));
    mp_sha256_final(&c, digest);
    auth_hex(digest, sizeof digest, out);
    return 0;
}

int auth_make_hash(const char *password, char *out, int outcap)  /* salt:hex */
{
    char salt[33], h[AUTH_HASH_LEN + 1];
    if (auth_make_salt(salt, sizeof salt) < 0) return -1;
    if (auth_pass_hash(salt, password, h, sizeof h) < 0) return -1;
    snprintf(out, outcap, "%s:%s", salt, h);
    return 0;
}

int hash_matches(const char *stored, const char *password)
{
    if (!stored || !stored[0] || !password) return 0;
    char tmp[160];
    snprintf(tmp, sizeof tmp, "%s", stored);
    char *colon = strchr(tmp, ':');
    if (!colon) return 0;
    *colon = 0;
    char want[AUTH_HASH_LEN + 1];
    if (auth_pass_hash(tmp, password, want, sizeof want) != 0) return 0;
    if (strlen(colon + 1) != AUTH_HASH_LEN) return 0;
    return memcmp(want, colon + 1, AUTH_HASH_LEN) == 0;
}

int pin_set(void)                       /* panel.pin 是否已设（访问屏障开启） */
{
    char *v = settings_get_value("panel.pin");
    int s = (v && v[0]) ? 1 : 0;
    free(v);
    return s;
}

int auth_pass_set(void)                 /* 旧密码是否已设（兼容迁移用） */
{
    char *v = settings_get_value("panel.auth_pass");
    int s = (v && v[0]) ? 1 : 0;
    free(v);
    return s;
}

int auth_verify(const char *password)   /* 旧密码校验（迁移期；见 login） */
{
    char *stored = settings_get_value("panel.auth_pass");
    int ok = hash_matches(stored, password);
    free(stored);
    return ok;
}

int pin_verify(const char *pin)         /* PIN 校验 */
{
    char *stored = settings_get_value("panel.pin");
    int ok = hash_matches(stored, pin);
    free(stored);
    return ok;
}

int pin_validate(const char *pin)
{
    if (!pin) return 0;
    size_t l = strlen(pin);
    if (l != 4) return 0;
    for (size_t i = 0; i < l; i++)
        if (pin[i] < '0' || pin[i] > '9') return 0;
    return 1;
}

long long pin_lock_remaining(void)      /* 剩余锁定秒；0=未锁 */
{
    time_t now = time(NULL);
    if (g_pin_locked_until <= now) return 0;
    return (long long)(g_pin_locked_until - now);
}

void pin_lock_reset(void)
{
    g_pin_fails = 0;
    g_pin_locked_until = 0;
}

void pin_record_fail(void)
{
    if (++g_pin_fails >= PIN_MAX_FAILS) {
        g_pin_locked_until = time(NULL) + PIN_LOCK_SEC;
        g_pin_fails = 0;
    }
}

int sess_find(const char *token)
{
    for (int i = 0; i < g_sess_n; i++)
        if (!strcmp(g_sess[i].token, token)) return i;
    return -1;
}

int sess_valid(const char *token)
{
    int i = sess_find(token);
    if (i < 0) return 0;
    if (g_sess[i].expires > 0 && time(NULL) >= g_sess[i].expires) return 0;
    return 1;
}

void sess_add(const char *token, time_t expires)
{
    int i = sess_find(token);
    if (i >= 0) { g_sess[i].expires = expires; return; }
    if (g_sess_n >= AUTH_MAX_SESS) {           /* 满：淘汰最早过期的一条 */
        int e = 0;
        for (int k = 1; k < g_sess_n; k++)
            if (g_sess[k].expires < g_sess[e].expires) e = k;
        if (e < g_sess_n - 1)
            memmove(&g_sess[e], &g_sess[e + 1], (size_t)(g_sess_n - 1 - e) * sizeof(auth_sess_t));
        g_sess_n--;
    }
    snprintf(g_sess[g_sess_n].token, sizeof g_sess[g_sess_n].token, "%s", token);
    g_sess[g_sess_n].expires = expires;
    g_sess_n++;
}

void sess_remove(const char *token)
{
    int i = sess_find(token);
    if (i < 0) return;
    if (i < g_sess_n - 1)
        memmove(&g_sess[i], &g_sess[i + 1], (size_t)(g_sess_n - 1 - i) * sizeof(auth_sess_t));
    g_sess_n--;
}

void auth_cp(char *dst, int dcap, const char *src)   /* 有界拷贝（防 -Wformat-truncation） */
{
    size_t l = strlen(src);
    if (l >= (size_t)dcap) l = (size_t)dcap - 1;
    memcpy(dst, src, l);
    dst[l] = 0;
}

int extract_token(const req_t *r, char *out, int outcap)
{
    out[0] = 0;
    if (r->x_meow_token[0]) { auth_cp(out, outcap, r->x_meow_token); return out[0] ? 1 : 0; }
    if (!strncasecmp(r->authorization, "Bearer ", 7)) {
        auth_cp(out, outcap, r->authorization + 7);
        return out[0] ? 1 : 0;
    }
    if (r->cookie[0]) {
        const char *p = strstr(r->cookie, "meow_token=");
        if (p) {
            p += 11;
            const char *e = p;
            while (*e && *e != ';' && *e != ' ' && *e != '\t') e++;
            size_t l = (size_t)(e - p);
            if (l >= (size_t)outcap) l = (size_t)outcap - 1;
            memcpy(out, p, l);
            out[l] = 0;
            return out[0] ? 1 : 0;
        }
    }
    return 0;
}

int require_auth(int sock, const req_t *r)
{
    const char *p = r->path;
    if (!strcmp(p, "/api/auth/login") || !strcmp(p, "/api/auth/logout") ||
        !strcmp(p, "/api/auth/status") || !strcmp(p, "/api/auth/setup")) return 1;
    char t[65];
    if (extract_token(r, t, sizeof t) && t[0] && sess_valid(t)) return 1;
    return send_err(sock, 401, "UNAUTHORIZED", "未认证或会话已失效");
}

int api_auth_status(int sock, const req_t *r)
{
    int ps = pin_set();
    int lg = auth_pass_set();
    int sess = 0;
    char t[65];
    if (extract_token(r, t, sizeof t) && t[0]) sess = sess_valid(t);
    long long rem = pin_lock_remaining();
    sbuf_t s = {0};
    sA(&s, "{\"auth_enabled\":true,\"session\":%s,\"pin_set\":%s,\"legacy\":%s,\"locked\":%s",
       sess ? "true" : "false", ps ? "true" : "false", lg ? "true" : "false", rem > 0 ? "true" : "false");
    if (rem > 0) sA(&s, ",\"lock_remaining_ms\":%lld", rem * 1000LL);
    sA(&s, "}");
    int rc = send_json(sock, 200, s.b ? s.b : "{}");
    sbuf_free(&s);
    return rc;
}

int api_auth_login(int sock, const req_t *r)
{
    if (!r->body || !r->body[0]) return send_err(sock, 400, "BAD_REQUEST", "缺少 PIN");
    jv_t *root = jv_parse(r->body, (int)r->body_len);
    if (!root) return send_err(sock, 400, "BAD_REQUEST", "body 非合法 JSON");
    jv_t *jpin = jv_obj_get(root, "pin");
    jv_t *jpw  = jv_obj_get(root, "password");
    char pin[8], pw[256];
    if (jpin && jpin->type == J_STR && jpin->str) snprintf(pin, sizeof pin, "%s", jpin->str); else pin[0] = 0;
    if (jpw && jpw->type == J_STR && jpw->str) snprintf(pw, sizeof pw, "%s", jpw->str); else pw[0] = 0;
    jv_free(root);

    if (pin_lock_remaining() > 0) {                          /* 已在锁定期 */
        sbuf_t e = {0};
        sA(&e, "{\"ok\":false,\"error\":{\"code\":\"LOCKED\",\"message\":\"已锁定，请稍后重试\"},\"lock_remaining_ms\":%lld}",
           pin_lock_remaining() * 1000LL);
        int rc = send_json(sock, 429, e.b ? e.b : "");
        sbuf_free(&e);
        return rc;
    }

    int use_legacy = 0;
    const char *cred = NULL;
    if (pin_set()) { cred = pin; if (!cred || !cred[0]) return send_err(sock, 400, "BAD_REQUEST", "缺少 pin 字段"); }
    else if (auth_pass_set()) { use_legacy = 1; cred = pw; if (!cred || !cred[0]) return send_err(sock, 400, "BAD_REQUEST", "缺少 password 字段"); }
    else return send_err(sock, 400, "BAD_REQUEST", "请先设置面板 PIN（/api/auth/setup）");

    int ok = use_legacy ? auth_verify(cred) : pin_verify(cred);
    if (!ok) {
        pin_record_fail();
        if (pin_lock_remaining() > 0) {                      /* 本错已触发锁定 */
            sbuf_t e = {0};
            sA(&e, "{\"ok\":false,\"error\":{\"code\":\"LOCKED\",\"message\":\"连续错误次数过多，已锁定 5 分钟\"},\"lock_remaining_ms\":%lld}",
               pin_lock_remaining() * 1000LL);
            int rc = send_json(sock, 429, e.b ? e.b : "");
            sbuf_free(&e);
            return rc;
        }
        return send_err(sock, 401, "UNAUTHORIZED", "PIN 错误");
    }
    pin_lock_reset();
    char token[65];
    if (auth_token_gen(token, sizeof token) < 0) return send_err(sock, 500, "INTERNAL", "生成会话失败");
    time_t exp = time(NULL) + g_auth_ttl;                    /* 固定 3 天（MEOW_AUTH_TTL 可覆盖测试用），不滑动续期 */
    sess_add(token, exp);
    sbuf_t s = {0};
    sA(&s, "{\"token\":");
    sA_str(&s, token);
    sA(&s, ",\"expires_at\":%lld,\"auth_enabled\":true}", (long long)exp);
    int rc = send_json(sock, 200, s.b ? s.b : "{}");
    sbuf_free(&s);
    return rc;
}

int api_auth_setup(int sock, const req_t *r)
{
    if (pin_set()) return send_err(sock, 409, "CONFLICT", "面板 PIN 已设置，请直接登录");
    if (!r->body || !r->body[0]) return send_err(sock, 400, "BAD_REQUEST", "缺少 PIN");
    jv_t *root = jv_parse(r->body, (int)r->body_len);
    if (!root) return send_err(sock, 400, "BAD_REQUEST", "body 非合法 JSON");
    jv_t *jpin = jv_obj_get(root, "pin");
    char pin[8];
    if (jpin && jpin->type == J_STR && jpin->str) snprintf(pin, sizeof pin, "%s", jpin->str);
    else pin[0] = 0;
    jv_free(root);
    if (!pin_validate(pin)) return send_err(sock, 422, "UNSUPPORTED", "PIN 必须为 4 位数字");
    char h[200];
    if (auth_make_hash(pin, h, sizeof h) < 0) return send_err(sock, 500, "INTERNAL", "生成 PIN 哈希失败");
    if (settings_write_one("panel.pin", h) < 0) return send_err(sock, 500, "INTERNAL", "写设置失败");
    pin_lock_reset();
    return send_json(sock, 200, "{\"pin_set\":true}");
}

int api_auth_logout(int sock, const req_t *r)
{
    char t[65];
    if (extract_token(r, t, sizeof t) && t[0]) sess_remove(t);
    return send_json(sock, 200, "{\"logged_out\":true}");
}

#undef MP_ROR
#undef MP_CH
#undef MP_MAJ
#undef MP_BSIG0
#undef MP_BSIG1
#undef MP_SSIG0
#undef MP_SSIG1