#include "kvstore.h"
#include "kvs_rw_tools.h"
#include <arpa/inet.h>
#include <unistd.h>

#if ENABLE_ARRAY
extern kvs_array_t global_array;
#endif

#if ENABLE_RBTREE
extern kvs_rbtree_t global_rbtree;
#endif

#if ENABLE_HASH
extern kvs_hash_t global_hash;
#endif

extern int global_cmd_log_fd;

// 0 suc, -1 err
int kvs_need(const uint8_t *p, const uint8_t *end, size_t n) {
	return (p + n <= end) ? 0 : -1;
}

// 注意u8类型不需要ntoh或者hton
// 0 suc, -1 err
int kvs_read_u8(const uint8_t **pp, const uint8_t *end, uint8_t *out) {
	const uint8_t *p = *pp;
	if (kvs_need(p, end, 1) < 0) return -1;
	*out = *p;
	*pp = p + 1;
	return 0;
}

int kvs_read_u16(const uint8_t **pp, const uint8_t *end, uint16_t *out) {
	const uint8_t *p = *pp;
	if (kvs_need(p, end, 2) < 0) return -1;
	uint16_t v;
	memcpy(&v, p, 2);
	*out = ntohs(v);
	*pp = p + 2;
	return 0;
}

int kvs_read_u32(const uint8_t **pp, const uint8_t *end, uint32_t *out) {
	const uint8_t *p = *pp;
	if (kvs_need(p, end, 4) < 0) return -1;
	uint32_t v;
	memcpy(&v, p, 4);
	*out = ntohl(v);
	*pp = p + 4;
	return 0;
}

int kvs_write_u8(uint8_t **pp, const uint8_t *end, uint8_t v) {
	uint8_t *p = *pp;
	if (kvs_need(p, end, 1) < 0) return -1;
	*p = v;
	*pp = p + 1;
	return 0;
}

int kvs_write_u16(uint8_t **pp, const uint8_t *end, uint16_t v) {
	uint8_t *p = *pp;
	if (kvs_need(p, end, 2) < 0) return -1;
	uint16_t be = htons(v);
	memcpy(p, &be, 2);
	*pp = p + 2;
	return 0;
}

int kvs_write_u32(uint8_t **pp, const uint8_t *end, uint32_t v) {
	uint8_t *p = *pp;
	if (kvs_need(p, end, 4) < 0) return -1;
	uint32_t be = htonl(v);
	memcpy(p, &be, 4);
	*pp = p + 4;
	return 0;
}

// -1 err, 0 suc
int kvs_write_file(FILE *fp, const void *buf, size_t n) {
    const uint8_t *p = (const uint8_t *)buf;
    while (n > 0) {
        size_t w = fwrite(p, 1, n, fp);
        if (w == 0) return -1;
        p += w;
        n -= w;
    }
    return 0;
}

// -1 err, 0 suc
int kvs_read_file(FILE *fp, void *buf, size_t n){
	uint8_t *p = (uint8_t *)buf;
    while (n > 0) {
        size_t r = fread(p, 1, n, fp);
        if (r == 0) return -1; // EOF or error
        p += r;
        n -= r;
    }
    return 0;
}


// return: -1 fail, 0 half, >0 consumed
int kvs_parse_one_cmd(const uint8_t *request, int request_length, kvs_req_t *req_out){
	if (!request || request_length <= 0 || !req_out) return -1;
	
	req_out->op = 0;
    req_out->argc = 0;
    req_out->args = NULL;

	const uint8_t *p = request;
    const uint8_t *end = request + (size_t)request_length;

	// OP + ARGC 
    if (kvs_need(p, end, 2)) {
        return 0; // NEED_MORE
    }

	uint8_t op = 0, argc = 0;
	if (kvs_read_u8(&p, end, &op) < 0) return -1;
	if (kvs_read_u8(&p, end, &argc) < 0) return -1;

	if (argc > KVS_MAX_ARGC) return -1;

	// 先扫描一遍确认整条命令数据都在 buffer 里
	const uint8_t *scan = p;
	uint32_t lens[KVS_MAX_ARGC];
	if (argc > 0) {
		for (uint8_t i = 0; i < argc; i++) {
			if (kvs_need(scan, end, 4)) {
				return 0; // NEED_MORE
			}
			uint32_t alen = 0;
			if (kvs_read_u32(&scan, end, &alen) < 0) return -1;

			// 防御：单个参数长度限制
			if (alen > KVS_MAX_ARGLEN) return -1;

			// 防御：scan + alen 越界 / 半包
			if (kvs_need(scan, end, (size_t)alen)) {
				return 0; // NEED_MORE
			}
			lens[i] = alen;
			scan += alen;
        }
	}

	size_t total_len = (size_t)(scan - request);
    if (total_len > KVS_MAX_CMD_BYTES) return -1;

	req_out->op = op;
    req_out->argc = argc;

	if (argc == 0) {
        return (int)total_len;
    }

	kvs_arg_t *args = (kvs_arg_t *)kvs_malloc((size_t)argc * sizeof(kvs_arg_t));
    if (!args) {
        kvs_free_request(req_out);
        return -1;
    }
	memset(args, 0, (size_t)argc * sizeof(kvs_arg_t));

	for (uint8_t i = 0; i < argc; i++) {
        uint32_t alen = 0;
        if (kvs_read_u32(&p, end, &alen) < 0) {
            kvs_free(args);
            kvs_free_request(req_out);
            return -1;
        }

        // alen 与 lens[i] 应当一致（扫描时读过），不一致说明解析器/输入异常
        if (alen != lens[i]) {
            kvs_free(args);
            kvs_free_request(req_out);
            return -1;
        }

        args[i].len = alen;
        args[i].data = p;     // 直接指向输入 buffer（零拷贝）
        p += alen;
    }

	
    req_out->args = args;

    return (int)(p - request);
}

void kvs_free_request(kvs_req_t *req) {
    if (!req) return;
    if (req->args) {
        kvs_free(req->args);
        req->args = NULL;
    }
    req->op = 0;
    req->argc = 0;
}

/**
 * 输入：req
 * 输出：rsp
 * 返回：-1 失败，参数错误，0 成功
 */
 int kvs_execute_one_cmd(const kvs_req_t *req, kvs_rsp_t *rsp_out) {
	if(!req || !rsp_out) return -1;
	rsp_out->op = req->op;
	rsp_out->status = KVS_STATUS_ERROR;
	rsp_out->data = NULL;
	rsp_out->dlen = 0;

	int argc = req->argc;
	int op = req->op;
	kvs_arg_t *argv = req->args;

	uint32_t key_len = 0;
	const void *key = NULL;
	uint32_t value_len = 0;
	const void *val = NULL;

	if(argc == 1){
		key_len = argv[0].len;
		key = argv[0].data;
	}else if(argc == 2){
		key_len = argv[0].len;
		key = argv[0].data;
		value_len = argv[1].len;
		val = argv[1].data;
	}

	// 基本参数校验（按你原有命令语义）
	switch (op) {
	case KVS_CMD_SET:
	case KVS_CMD_MOD:
	case KVS_CMD_RSET:
	case KVS_CMD_RMOD:
	case KVS_CMD_HSET:
	case KVS_CMD_HMOD:
		if (argc != 2 || !key || !val) { rsp_out->status = KVS_STATUS_BADREQ; return -1; }
		break;
	case KVS_CMD_GET:
	case KVS_CMD_DEL:
	case KVS_CMD_EXIST:
	case KVS_CMD_RGET:
	case KVS_CMD_RDEL:
	case KVS_CMD_REXIST:
	case KVS_CMD_HGET:
	case KVS_CMD_HDEL:
	case KVS_CMD_HEXIST:
		if (argc != 1 || !key) { rsp_out->status = KVS_STATUS_BADREQ; return -1; }
		break;
	case KVS_CMD_SAVE:
		if(argc != 0) { rsp_out->status = KVS_STATUS_BADREQ; return -1; }
		break;
	default:
		rsp_out->status = KVS_STATUS_BADREQ;
		return -1;
	}

	int ret = 0;
	const char *result = NULL;

	switch (op) {
#if ENABLE_ARRAY
	case KVS_CMD_SET:
		ret = kvs_array_set_bin(&global_array, key, key_len, val, value_len);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_EXIST;
		return 0;

	case KVS_CMD_GET:
		result = kvs_array_get_bin(&global_array, key, key_len, &value_len);
		if (!result) { rsp_out->status = KVS_STATUS_NO_EXIST; return 0; }
		rsp_out->status = KVS_STATUS_OK;
		rsp_out->data = result;
		rsp_out->dlen = (uint32_t)value_len;
		return 0;

	case KVS_CMD_DEL:
		ret = kvs_array_del_bin(&global_array, key, key_len);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_NO_EXIST;
		return 0;

	case KVS_CMD_MOD:
		ret = kvs_array_mod_bin(&global_array, key, key_len, val, value_len);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_NO_EXIST;
		return 0;

	case KVS_CMD_EXIST:
		ret = kvs_array_exist_bin(&global_array, key, key_len);
		rsp_out->status = (ret == 0) ? KVS_STATUS_EXIST : KVS_STATUS_NO_EXIST;
		return 0;
#endif

#if ENABLE_RBTREE
	case KVS_CMD_RSET:
		ret = kvs_rbtree_set(&global_rbtree, (char*)key, (char*)val);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_EXIST;
		return 0;

	case KVS_CMD_RGET:
		result = kvs_rbtree_get(&global_rbtree, (char*)key);
		if (!result) { rsp_out->status = KVS_STATUS_NO_EXIST; return 0; }
		rsp_out->status = KVS_STATUS_OK;
		rsp_out->data = result;
		rsp_out->dlen = (uint32_t)strlen(result);
		return 0;

	case KVS_CMD_RDEL:
		ret = kvs_rbtree_del(&global_rbtree, (char*)key);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_NO_EXIST;
		return 0;

	case KVS_CMD_RMOD:
		ret = kvs_rbtree_mod(&global_rbtree, (char*)key, (char*)val);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_NO_EXIST;
		return 0;

	case KVS_CMD_REXIST:
		ret = kvs_rbtree_exist(&global_rbtree, (char*)key);
		rsp_out->status = (ret == 0) ? KVS_STATUS_EXIST : KVS_STATUS_NO_EXIST;
		return 0;
#endif

#if ENABLE_HASH
	case KVS_CMD_HSET:
		ret = kvs_hash_set_bin(&global_hash, key, key_len, val, value_len);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_EXIST;
		return 0;

	case KVS_CMD_HGET:
		result = kvs_hash_get_bin(&global_hash, key, key_len, &value_len);
		if (!result) { rsp_out->status = KVS_STATUS_NO_EXIST; return 0; }
		rsp_out->status = KVS_STATUS_OK;
		rsp_out->data = result;
		rsp_out->dlen = (uint32_t)value_len;
		return 0;

	case KVS_CMD_HDEL:
		ret = kvs_hash_del_bin(&global_hash, key, key_len);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_NO_EXIST;
		return 0;

	case KVS_CMD_HMOD:
		ret = kvs_hash_mod_bin(&global_hash, key, key_len, val, value_len);
		if (ret < 0) rsp_out->status = KVS_STATUS_ERROR;
		else if (ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_NO_EXIST;
		return 0;

	case KVS_CMD_HEXIST:
		ret = kvs_hash_exist_bin(&global_hash, key, key_len);
		rsp_out->status = (ret == 0) ? KVS_STATUS_EXIST : KVS_STATUS_NO_EXIST;
		return 0;
#endif
	case KVS_CMD_SAVE:
		ret = kvs_save_to_file();
		if(ret == 0) rsp_out->status = KVS_STATUS_OK;
		else rsp_out->status = KVS_STATUS_ERROR;
		return 0;
	default:
		rsp_out->status = KVS_STATUS_BADREQ;
		return -1;
	}

	return -1;
}

/**
 * 构建单条响应
 * 返回：-1 失败，>=0 响应长度
 */
int kvs_build_one_rsp(const kvs_rsp_t *results, uint8_t *response, size_t response_cap){
	if (!results || !response) return -1;

	const uint8_t *end = response + response_cap;
    uint8_t *p = response;

    // 计算所需长度：1 + 1 + 4 + dlen
    // 注意防止 size_t 溢出
    size_t need = 1u + 1u + 4u + (size_t)results->dlen;
    if (need > response_cap) return -1;

    if (kvs_write_u8(&p, end, results->op) < 0) return -1;
    if (kvs_write_u8(&p, end, results->status) < 0) return -1;
    if (kvs_write_u32(&p, end, results->dlen) < 0) return -1;

    if (results->dlen > 0) {
        if (!results->data) return -1; // 有长度却没指针，视为错误
        if (kvs_need(p, end, (size_t)results->dlen) < 0) return -1;
        memcpy(p, results->data, results->dlen);
        p += results->dlen;
    }

    return (int)(p - response);
}

int kvs_save_to_file(){
	#if ENABLE_ARRAY
	int ret = kvs_array_save(&global_array, KVS_ARRAY_FILE);
	#endif

	#if ENABLE_RBTREE

	#endif

	#if ENABLE_HASH

	#endif

	ksv_clear_log(global_cmd_log_fd);

	return ret;
}

#include <errno.h>
int write_full(int fd, const void *buf, size_t len)
{
    const uint8_t *p = buf;

    while (len > 0) {
        ssize_t n = write(fd, p, len);
        if (n < 0) {
            if (errno == EINTR)
                continue;
            return -1;
        }
        p += n;
        len -= n;
    }
    return 0;
}

// 1 read n suc, 0 eof, -1 error
int read_full(int fd, void *buf, size_t n)
{
    uint8_t *p = (uint8_t *)buf;
    size_t got = 0;

    while (got < n) {
        ssize_t r = read(fd, p + got, n - got);
        if (r > 0) {
            got += (size_t)r;
            continue;
        }
        if (r == 0) {
            return (got == 0) ? 0 : -1;
        }
        /* r < 0 */
        if (errno == EINTR) {
            continue;
        }
        return -1;
    }

    return 1;
}

int kvs_save_cmd_to_logfile(const uint8_t *cmd, size_t len, int logfd){
	if (logfd < 0 || !cmd || len == 0)
        return -1;

    if (len > UINT32_MAX)
        return -2;

    uint32_t nlen = htonl((uint32_t)len);

    if (write_full(logfd, &nlen, sizeof(nlen)) < 0)
        return -3;

    if (write_full(logfd, cmd, len) < 0)
        return -4;

	if (fsync(logfd) < 0)
        return -5;

	return 0;
}

int	kvs_replay_log(const char *logfile, int logfd){
	 if (!logfile|| logfd<0) return -1;

    for (;;) {
        uint32_t nlen = 0;

        int hr = read_full(logfd, &nlen, sizeof(nlen));
        if (hr == 0) break;          /* EOF：正常结束 */
        if (hr < 0) { return -2; }  /* 半截头 */

        uint32_t len = ntohl(nlen);
        if (len == 0) { return -3; }

        uint8_t *cmd = (uint8_t *)kvs_malloc(len);
        if (!cmd) { return -5; }

        int pr = read_full(logfd, cmd, len);
        if (pr <= 0) { /* 半截 payload */
            kvs_free(cmd);
            return -6;
        }

        kvs_req_t req;
        memset(&req, 0, sizeof(req));

        int clen = kvs_parse_one_cmd(cmd, (int)len, &req);
        if (clen <= 0 || clen != (int)len) {
            kvs_free_request(&req);
            kvs_free(cmd);
            return -7;
        }

        kvs_rsp_t rsp;
        memset(&rsp, 0, sizeof(rsp));

        if (kvs_execute_one_cmd(&req, &rsp) < 0) {
            kvs_free_request(&req);
            kvs_free(cmd);
            return -8;
        }

        kvs_free_request(&req);
        kvs_free(cmd);
    }

    return 0;
}

/**
 * clear log file not close
 */
int ksv_clear_log(int logfd){
	if(logfd < 0) return -1;
	ftruncate(logfd, 0);
	lseek(logfd, 0, SEEK_SET);
	return 0;
}