/* lock_screen.c — MeowOS 锁屏 4 位 PIN（纯逻辑；宿主可单测 lock_screen.h）。
 *
 * 与 meowpanel.c 的访问级 PIN（PANEL_ENHANCE_PLAN）**同源同格式**：`<salt_hex>:<sha256_hex(salt||pin)>`。
 * 内联 SHA-256 取自 meow_verify/sha256.c（FIPS 180-4，公有领域参考写法），前缀 lck_ 避免符号冲突；
 * 算法与 meowpanel.c 的 mp_sha256 逐字一致 → 面板生成的 panel.pin 无需重设即可被本模块校验。
 *
 * 日志用 fprintf(stderr)（前缀 [lock]），不依赖 launcher 的 logmsg —— 宿主测试可直接 #include 本文件。
 * 依赖 meow_settings_* API（同一 settings.conf），持久化走 meow_settings_save()（含 boot.default
 * 同步，幂等）。
 */
#include "lock_screen.h"
#include "meow_settings.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <fcntl.h>
#include <unistd.h>

#define LCK_LOG(...) fprintf(stderr, "[lock] " __VA_ARGS__)

/* ---- 最小 SHA-256（FIPS 180-4，公有领域参考写法；内联拷贝自 meow_verify/sha256.c，前缀 lck_） ---- */
static const uint32_t lck_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
};
#define LCK_ROR(x,n)  (((x) >> (n)) | ((x) << (32 - (n))))
#define LCK_CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
#define LCK_MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define LCK_BSIG0(x)  (LCK_ROR(x,2) ^ LCK_ROR(x,13) ^ LCK_ROR(x,22))
#define LCK_BSIG1(x)  (LCK_ROR(x,6) ^ LCK_ROR(x,11) ^ LCK_ROR(x,25))
#define LCK_SSIG0(x)  (LCK_ROR(x,7) ^ LCK_ROR(x,18) ^ ((x) >> 3))
#define LCK_SSIG1(x)  (LCK_ROR(x,17) ^ LCK_ROR(x,19) ^ ((x) >> 10))

typedef struct lck_sha256_ctx {
    uint32_t state[8];
    uint64_t count;
    uint8_t  buf[64];
    size_t   buflen;
} lck_sha256_ctx;

static void lck_sha256_init(lck_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;
}

static void lck_sha256_block(lck_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] = LCK_SSIG1(w[i-2]) + w[i-7] + LCK_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 + LCK_BSIG1(e) + LCK_CH(e,f,g) + lck_sha256_k[i] + w[i];
        uint32_t t2 = LCK_BSIG0(a) + LCK_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;
}

static void lck_sha256_update(lck_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) { lck_sha256_block(c, c->buf); c->buflen = 0; }
    }
    while (len >= 64) { lck_sha256_block(c, data); data += 64; len -= 64; }
    if (len) { memcpy(c->buf, data, len); c->buflen = len; }
}

static void lck_sha256_final(lck_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;
        lck_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));
    lck_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]);
    }
}
#undef LCK_ROR
#undef LCK_CH
#undef LCK_MAJ
#undef LCK_BSIG0
#undef LCK_BSIG1
#undef LCK_SSIG0
#undef LCK_SSIG1

/* ---- 哈希基元（格式 `<salt_hex>:<sha256_hex(salt||pin)>`，与面板全等）---- */
static void lck_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;
}

static int lck_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;
}

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

static int lck_pass_hash(const char *salt, const char *password, char *out, int outcap)
{
    lck_sha256_ctx c;
    uint8_t digest[32];
    if (outcap < LCK_HASH_LEN + 1) return -1;
    lck_sha256_init(&c);
    lck_sha256_update(&c, (const uint8_t *)salt, strlen(salt));
    lck_sha256_update(&c, (const uint8_t *)password, strlen(password));
    lck_sha256_final(&c, digest);
    lck_hex(digest, sizeof digest, out);
    return 0;
}

static int lck_make_hash(const char *password, char *out, int outcap)  /* salt:hex */
{
    char salt[33], h[LCK_HASH_LEN + 1];
    if (lck_make_salt(salt, sizeof salt) < 0) return -1;
    if (lck_pass_hash(salt, password, h, sizeof h) < 0) return -1;
    snprintf(out, (size_t)outcap, "%s:%s", salt, h);
    return 0;
}

/* 校验 `salt:hex` 是否匹配明文（恒定比较，不反解）。stored 为 `salt:hex` 完整串。 */
static int lck_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[LCK_HASH_LEN + 1];
    if (lck_pass_hash(tmp, password, want, sizeof want) != 0) return 0;
    if (strlen(colon + 1) != LCK_HASH_LEN) return 0;
    return memcmp(want, colon + 1, LCK_HASH_LEN) == 0;
}

/* ---- 设置读取辅助（NULL 表示键缺失/空）---- */
static char *lck_get(const char *key)
{
    char buf[MEOW_SET_MAX_LEN];
    if (meow_settings_get_str(key, buf, sizeof buf) != 0) return NULL;
    if (!buf[0]) return NULL;              /* 空值=未设 */
    char *r = strdup(buf);
    return r;
}
static int lck_get_int(const char *key)
{
    int v = 0;
    if (meow_settings_get_int(key, &v) != 0) v = 0;
    return v;
}
static int lck_set_int(const char *key, int v)
{
    return meow_settings_set_int(key, v);
}
static int lck_persist(void)
{
    return meow_settings_save();
}

/* ---- 公开接口 ---- */
int lck_pin_valid(const char *pin)
{
    if (!pin) return 0;
    size_t l = strlen(pin);
    if (l != LCK_PIN_LEN) return 0;
    for (size_t i = 0; i < l; i++)
        if (pin[i] < '0' || pin[i] > '9') return 0;
    return 1;
}

int lck_pin_configured(void)
{
    char *sp = lck_get(LCK_KEY_PIN);
    int s = (sp != NULL);
    free(sp);
    if (s) return 1;
    char *pp = lck_get(LCK_KEY_PANEL_PIN);
    int p = (pp != NULL);
    free(pp);
    return p;
}

int lck_lock_required(int allow_disable)
{
    if (!lck_pin_configured()) return 0;      /* 未设凭据：锁屏无鉴别物，不开 */
    if (allow_disable) {
        int wake = 1;
        if (meow_settings_get_int(LCK_KEY_WAKE, &wake) != 0) wake = 1;
        return wake ? 1 : 0;
    }
    return 1;                                  /* 手动锁：不看 WAKE 键 */
}

int lck_pin_check(const char *pin)
{
    if (!lck_pin_valid(pin)) return 0;
    char *sp = lck_get(LCK_KEY_PIN);
    if (sp) {
        int ok = lck_hash_matches(sp, pin);
        free(sp);
        return ok;
    }
    /* system.pin 未设：迁移期回退校验 panel.pin */
    char *pp = lck_get(LCK_KEY_PANEL_PIN);
    if (pp) {
        int ok = lck_hash_matches(pp, pin);
        free(pp);
        return ok;
    }
    return 0;
}

int lck_pin_set(const char *pin)
{
    if (!lck_pin_valid(pin)) return MEOW_ERR_INVAL;
    char hash[160];   /* 32(salt) + ':' + 64(sha256 hex) + NUL = 98 */
    if (lck_make_hash(pin, hash, sizeof hash) != 0) return MEOW_ERR_IO;
    if (meow_settings_set_str(LCK_KEY_PIN, hash) != MEOW_OK) return MEOW_ERR_INVAL;
    lck_set_int(LCK_KEY_FAILS, 0);
    lck_set_int(LCK_KEY_LOCK_UNTIL, 0);
    lck_persist();
    LCK_LOG("pin set (%d digits, hash stored salt:sha256)\n", LCK_PIN_LEN);
    return MEOW_OK;
}

int lck_pin_clear(void)
{
    if (meow_settings_set_str(LCK_KEY_PIN, "") != MEOW_OK) return MEOW_ERR_INVAL;
    lck_set_int(LCK_KEY_FAILS, 0);
    lck_set_int(LCK_KEY_LOCK_UNTIL, 0);
    lck_persist();
    LCK_LOG("pin cleared (unlock)\n");
    return MEOW_OK;
}

int lck_pin_success(void)
{
    char *sp = lck_get(LCK_KEY_PIN);
    if (!sp) {
        /* 首次成功：把 panel.pin 并入 system.pin（一次性迁移），此后 system.pin 为准 */
        char *pp = lck_get(LCK_KEY_PANEL_PIN);
        if (pp) {
            meow_settings_set_str(LCK_KEY_PIN, pp);
            LCK_LOG("success: migrated panel.pin -> system.pin\n");
            free(pp);
        } else {
            LCK_LOG("success: no system.pin and no panel.pin?!\n");
        }
    }
    free(sp);
    lck_set_int(LCK_KEY_FAILS, 0);
    lck_set_int(LCK_KEY_LOCK_UNTIL, 0);
    lck_persist();
    return MEOW_OK;
}

int lck_pin_fail(void)
{
    time_t now = time(NULL);
    int fails = lck_get_int(LCK_KEY_FAILS);
    int until = lck_get_int(LCK_KEY_LOCK_UNTIL);
    /* 已锁定：不再递增（锁屏页本应禁输入；防御） */
    if (until > 0 && (time_t)until > now)
        return (int)((time_t)until - now);
    fails++;
    if (fails >= LCK_PIN_MAX_FAILS) {
        until = (int)now + LCK_PIN_LOCK_SEC;
        fails = 0;
        LCK_LOG("fail: %d consecutive -> LOCK %ds (until=%d)\n",
                LCK_PIN_MAX_FAILS, LCK_PIN_LOCK_SEC, until);
    } else {
        until = 0;
        LCK_LOG("fail: attempt %d/%d\n", fails, LCK_PIN_MAX_FAILS);
    }
    lck_set_int(LCK_KEY_FAILS, fails);
    lck_set_int(LCK_KEY_LOCK_UNTIL, until);
    lck_persist();
    return (until > 0 && (time_t)until > now) ? (int)((time_t)until - now) : 0;
}

time_t lck_lock_remaining(void)
{
    time_t now = time(NULL);
    int until = lck_get_int(LCK_KEY_LOCK_UNTIL);
    if (until > 0 && (time_t)until > now)
        return (time_t)until - now;
    if (until > 0) {
        /* 截止已过：清锁定戳+计数（进程内解禁），落盘 */
        LCK_LOG("lock expired (%d < now=%ld), clearing\n", until, (long)now);
        lck_set_int(LCK_KEY_LOCK_UNTIL, 0);
        lck_set_int(LCK_KEY_FAILS, 0);
        lck_persist();
    }
    return 0;
}

/* ---- 面板一次性解锁恢复口（tmpfs 标志）---- */
int lck_unlock_once_consume(void)
{
    if (access(LCK_UNLOCK_ONCE_FILE, F_OK) != 0) return 0;   /* 不存在：不影响 */
    unlink(LCK_UNLOCK_ONCE_FILE);
    LCK_LOG("unlock-once: bypass file present -> consume + release once\n");
    return 1;
}

int lck_manual_lock_set(void)
{
    int fd = open(LCK_MANUAL_LOCK_FILE, O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (fd < 0) { LCK_LOG("manual-lock: open %s fail\n", LCK_MANUAL_LOCK_FILE); return MEOW_ERR_IO; }
    write(fd, "1", 1); close(fd);
    LCK_LOG("manual-lock: set %s\n", LCK_MANUAL_LOCK_FILE);
    return MEOW_OK;
}

void lck_manual_lock_clear(void)
{
    if (access(LCK_MANUAL_LOCK_FILE, F_OK) == 0) {
        unlink(LCK_MANUAL_LOCK_FILE);
        LCK_LOG("manual-lock: cleared\n");
    }
}

int lck_wake_should_lock(void)
{
    if (!lck_pin_configured()) return 0;
    int wake = 1;
    if (meow_settings_get_int(LCK_KEY_WAKE, &wake) != 0) wake = 1;
    if (wake) return 1;
    /* 唤醒锁已关，但存在「主动锁」标志（电源菜单「锁定」）→ 仍必锁屏 */
    return access(LCK_MANUAL_LOCK_FILE, F_OK) == 0;
}