#include "proto.h"
#include <string.h>

const char *proto_locate(const char *json, const char *key)
{
    char pat[24];
    int klen = (int)strlen(key);
    const char *p = json;

    if (klen <= 0 || klen + 3 > (int)sizeof(pat)) return 0;
    pat[0] = '"';
    memcpy(pat + 1, key, klen);
    pat[klen + 1] = '"';
    pat[klen + 2] = '\0';

    while ((p = strstr(p, pat)) != 0) {
        const char *q = p + klen + 2;
        while (*q == ' ' || *q == '\t') q++;
        if (*q == ':') {
            q++;
            while (*q == ' ' || *q == '\t') q++;
            return q;
        }
        /* 命中的是字符串值里的子串而非键名，继续向后找 */
        p += 2;
    }
    return 0;
}

/* 提取 key 的值区域到 buf（带花括号深度跟踪，嵌套对象整体取出）。
 * 成功返回 1，失败返回 0。 */
static int proto_value_region(const char *json, const char *key, char *buf, int cap)
{
    const char *p = proto_locate(json, key);
    int i = 0;
    int depth = 0;

    if (!p) return 0;
    while (p[i] && i < cap - 1) {
        char c = p[i];
        if (c == '{') {
            depth++;
        } else if (c == '}') {
            if (depth == 0) break;      /* 不属于本值的右括号 */
            depth--;
            if (depth == 0) { i++; break; }  /* 嵌套对象结束 */
        } else if (c == ',' && depth == 0) {
            break;                      /* 顶层下一个字段 */
        }
        buf[i] = c;
        i++;
    }
    buf[i] = '\0';
    return 1;
}

int proto_get_bool(const char *json, const char *key, int *val)
{
    char region[96];
    char *q;
    int len;

    if (!proto_value_region(json, key, region, sizeof(region))) return 0;
    len = (int)strlen(region);

    /* 在值区域内找最先出现的 true/false 令牌（排除键名里的子串） */
    for (q = region; q < region + len; q++) {
        if (q + 4 <= region + len && strncmp(q, "true", 4) == 0 && (q == region || q[-1] != '"')) {
            *val = 1;
            return 1;
        }
        if (q + 5 <= region + len && strncmp(q, "false", 5) == 0 && (q == region || q[-1] != '"')) {
            *val = 0;
            return 1;
        }
    }

    /* 兼容 0/1 */
    if (region[0] == '0' || region[0] == '1') {
        *val = region[0] - '0';
        return 1;
    }
    return 0;
}

int proto_get_u32(const char *json, const char *key, uint32_t *val)
{
    const char *p = proto_locate(json, key);
    uint32_t v = 0;

    if (!p || *p < '0' || *p > '9') return 0;
    while (*p >= '0' && *p <= '9') {
        v = v * 10 + (uint32_t)(*p - '0');
        p++;
    }
    *val = v;
    return 1;
}

int proto_get_hex16(const char *json, const char *key, uint16_t *val)
{
    const char *p = proto_locate(json, key);
    uint16_t v = 0;
    int n = 0;

    if (!p) return 0;
    if (*p == '"') p++;
    while (n < 4) {
        char c = *p;
        uint8_t d;
        if (c >= '0' && c <= '9')      d = (uint8_t)(c - '0');
        else if (c >= 'a' && c <= 'f') d = (uint8_t)(c - 'a' + 10);
        else if (c >= 'A' && c <= 'F') d = (uint8_t)(c - 'A' + 10);
        else break;
        v = (uint16_t)((v << 4) | d);
        p++;
        n++;
    }
    if (n == 0) return 0;
    *val = v;
    return 1;
}

int proto_get_str(const char *json, const char *key, char *out, int cap)
{
    const char *p = proto_locate(json, key);
    int i = 0;

    if (!p || *p != '"' || cap <= 0) return 0;
    p++;
    while (p[i] && p[i] != '"' && i < cap - 1) {
        out[i] = p[i];
        i++;
    }
    out[i] = '\0';
    return (i > 0) ? 1 : 0;
}

int proto_get_id(const char *json, char *out, int cap)
{
    const char *p = proto_locate(json, "id");
    int i = 0;

    if (!p || cap <= 0) return 0;
    if (*p == '"') {
        p++;
        while (i < cap - 1 &&
               ((p[i] >= '0' && p[i] <= '9') ||
                (p[i] >= 'a' && p[i] <= 'z') ||
                (p[i] >= 'A' && p[i] <= 'Z'))) {
            out[i] = p[i];
            i++;
        }
    } else {
        while (i < cap - 1 && p[i] >= '0' && p[i] <= '9') {
            out[i] = p[i];
            i++;
        }
    }
    out[i] = '\0';
    return (i > 0) ? 1 : 0;
}

int proto_get_kg100(const char *json, const char *key, uint16_t *val)
{
    char region[64];
    const char *p;
    const char *vp;
    uint16_t v = 0;

    if (!proto_value_region(json, key, region, sizeof(region))) return 0;

    /* 嵌套对象时取 "value" 字段，否则直接用区域本身 */
    vp = proto_locate(region, "value");
    p = vp ? vp : region;

    /* 跳过空白、引号、冒号 */
    while (*p == ' ' || *p == '\t' || *p == '\r' || *p == '\n' || *p == '"' || *p == ':') p++;
    if (*p < '0' || *p > '9') return 0;

    while (*p >= '0' && *p <= '9') {
        v = (uint16_t)(v * 10 + (*p - '0'));
        p++;
    }
    if (*p == '.') {
        p++;
        if (*p >= '0' && *p <= '9') {
            v = (uint16_t)(v * 10 + (*p - '0'));
        } else {
            v = (uint16_t)(v * 10); /* 整数补一位小数 */
        }
        /* 忽略第二位小数 */
    } else {
        v = (uint16_t)(v * 10);     /* 整数转 0.1KG */
    }
    *val = v;
    return 1;
}