#include "rpc.h"

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include "json.h"

static int fd_write_all(int fd, const char *buf, size_t n) {
    size_t off = 0;
    while (off < n) {
        ssize_t w = write(fd, buf + off, n - off);
        if (w < 0) {
            if (errno == EINTR) {
                continue;
            }
            return 0;
        }
        off += (size_t)w;
    }
    return 1;
}

static char *fd_read_all(int fd) {
    size_t cap = 4096;
    size_t len = 0;
    char *out = (char *)malloc(cap);

    if (out == NULL) {
        return NULL;
    }

    while (1) {
        ssize_t r;
        if (len + 2048 + 1 > cap) {
            char *p;
            cap *= 2;
            p = (char *)realloc(out, cap);
            if (p == NULL) {
                free(out);
                return NULL;
            }
            out = p;
        }

        r = read(fd, out + len, cap - len - 1);
        if (r < 0) {
            if (errno == EINTR) {
                continue;
            }
            free(out);
            return NULL;
        }

        if (r == 0) {
            break;
        }

        len += (size_t)r;
    }

    out[len] = '\0';
    return out;
}

static int run_curl_rpc(const RpcClient *client, const char *payload, char **response_out) {
    int in_pipe[2];
    int out_pipe[2];
    pid_t pid;
    char auth[300];
    char url[300];
    int status;
    char *response;

    if (pipe(in_pipe) < 0 || pipe(out_pipe) < 0) {
        perror("pipe");
        return 0;
    }

    pid = fork();
    if (pid < 0) {
        perror("fork");
        close(in_pipe[0]);
        close(in_pipe[1]);
        close(out_pipe[0]);
        close(out_pipe[1]);
        return 0;
    }

    if (pid == 0) {
        close(in_pipe[1]);
        close(out_pipe[0]);

        dup2(in_pipe[0], STDIN_FILENO);
        dup2(out_pipe[1], STDOUT_FILENO);
        dup2(out_pipe[1], STDERR_FILENO);

        close(in_pipe[0]);
        close(out_pipe[1]);

        snprintf(auth, sizeof(auth), "%s:%s", client->cfg->rpc_user, client->cfg->rpc_password);
        snprintf(url, sizeof(url), "http://%s:%d/", client->cfg->rpc_host, client->cfg->rpc_port);

        execlp(
            "curl",
            "curl",
            "-s",
            "--connect-timeout",
            "5",
            "--max-time",
            "30",
            "--user",
            auth,
            "--data-binary",
            "@-",
            "-H",
            "content-type:text/plain;",
            url,
            (char *)NULL
        );
        _exit(127);
    }

    close(in_pipe[0]);
    close(out_pipe[1]);

    if (fd_write_all(in_pipe[1], payload, strlen(payload)) == 0) {
        close(in_pipe[1]);
        close(out_pipe[0]);
        kill(pid, SIGKILL);
        waitpid(pid, NULL, 0);
        return 0;
    }

    close(in_pipe[1]);

    response = fd_read_all(out_pipe[0]);
    close(out_pipe[0]);

    if (waitpid(pid, &status, 0) < 0) {
        free(response);
        return 0;
    }

    if (WIFEXITED(status) == 0 || WEXITSTATUS(status) != 0) {
        fprintf(stderr, "[rpc] curl fallita (status=%d)\n", status);
        free(response);
        return 0;
    }

    if (response == NULL || response[0] == '\0') {
        free(response);
        return 0;
    }

    *response_out = response;
    return 1;
}

static int token_is_null(const JsonDoc *doc, int tok_idx) {
    return json_token_streq(doc, tok_idx, "null");
}

static int rpc_call_result(const RpcClient *client, const char *method, const char *params_json, char **result_out) {
    char *payload;
    size_t payload_len;
    char *response = NULL;
    JsonDoc doc;
    int err_idx;
    int res_idx;
    char *result = NULL;

    payload_len = strlen(method) + strlen(params_json) + 128;
    payload = (char *)malloc(payload_len);
    if (payload == NULL) {
        return 0;
    }

    snprintf(
        payload,
        payload_len,
        "{\"jsonrpc\":\"1.0\",\"id\":\"easy-miner\",\"method\":\"%s\",\"params\":%s}",
        method,
        params_json
    );

    if (run_curl_rpc(client, payload, &response) == 0) {
        free(payload);
        return 0;
    }
    free(payload);

    if (json_doc_parse(&doc, response) == 0) {
        fprintf(stderr, "[rpc] JSON non valido in risposta a %s\n", method);
        free(response);
        return 0;
    }

    if (doc.token_count <= 0 || doc.tokens[0].type != JSMN_OBJECT) {
        json_doc_free(&doc);
        free(response);
        return 0;
    }

    err_idx = json_object_get(&doc, 0, "error");
    if (err_idx >= 0 && token_is_null(&doc, err_idx) == 0) {
        char *err_msg = json_token_strdup(&doc, err_idx);
        fprintf(stderr, "[rpc] errore RPC %s: %s\n", method, err_msg ? err_msg : "(unknown)");
        free(err_msg);
        json_doc_free(&doc);
        free(response);
        return 0;
    }

    res_idx = json_object_get(&doc, 0, "result");
    if (res_idx < 0) {
        json_doc_free(&doc);
        free(response);
        return 0;
    }

    result = json_token_strdup(&doc, res_idx);
    json_doc_free(&doc);
    free(response);

    if (result == NULL) {
        return 0;
    }

    *result_out = result;
    return 1;
}

static long long token_to_ll(const JsonDoc *doc, int tok_idx) {
    char *tmp = json_token_strdup(doc, tok_idx);
    long long v = 0;
    if (tmp != NULL) {
        v = strtoll(tmp, NULL, 10);
        free(tmp);
    }
    return v;
}

void rpc_init(RpcClient *client, const MinerConfig *cfg) {
    client->cfg = cfg;
}

int rpc_test_connection(RpcClient *client, char **chain_out) {
    char *result = NULL;
    JsonDoc doc;
    int chain_idx;

    if (rpc_call_result(client, "getblockchaininfo", "[]", &result) == 0) {
        return 0;
    }

    if (json_doc_parse(&doc, result) == 0) {
        free(result);
        return 0;
    }

    chain_idx = json_object_get(&doc, 0, "chain");
    if (chain_idx < 0) {
        json_doc_free(&doc);
        free(result);
        return 0;
    }

    *chain_out = json_token_strdup(&doc, chain_idx);

    json_doc_free(&doc);
    free(result);

    return (*chain_out != NULL);
}

int rpc_get_best_block_hash(RpcClient *client, char **hash_out) {
    return rpc_call_result(client, "getbestblockhash", "[]", hash_out);
}

int rpc_get_address_script_pubkey(RpcClient *client, const char *wallet_address, char **script_out) {
    char params[320];
    char *result = NULL;
    JsonDoc doc;
    int idx;

    snprintf(params, sizeof(params), "[\"%s\"]", wallet_address);

    if (rpc_call_result(client, "getaddressinfo", params, &result) == 0) {
        return 0;
    }

    if (json_doc_parse(&doc, result) == 0) {
        free(result);
        return 0;
    }

    idx = json_object_get(&doc, 0, "scriptPubKey");
    if (idx < 0) {
        json_doc_free(&doc);
        free(result);
        return 0;
    }

    *script_out = json_token_strdup(&doc, idx);

    json_doc_free(&doc);
    free(result);
    return (*script_out != NULL);
}

int rpc_get_raw_transaction(RpcClient *client, const char *txid, char **raw_tx_out) {
    char params[256];
    snprintf(params, sizeof(params), "[\"%s\",false]", txid);
    return rpc_call_result(client, "getrawtransaction", params, raw_tx_out);
}

int rpc_get_block_template(RpcClient *client, BlockTemplate *tpl) {
    char *result = NULL;
    JsonDoc doc;
    int idx_version;
    int idx_prev;
    int idx_curtime;
    int idx_bits;
    int idx_height;
    int idx_coinbase;
    int idx_wc;
    int idx_txs;
    int i;

    memset(tpl, 0, sizeof(*tpl));

    if (rpc_call_result(client, "getblocktemplate", "[{\"rules\":[\"segwit\"]}]", &result) == 0) {
        return 0;
    }

    if (json_doc_parse(&doc, result) == 0) {
        free(result);
        return 0;
    }

    idx_version = json_object_get(&doc, 0, "version");
    idx_prev = json_object_get(&doc, 0, "previousblockhash");
    idx_curtime = json_object_get(&doc, 0, "curtime");
    idx_bits = json_object_get(&doc, 0, "bits");
    idx_height = json_object_get(&doc, 0, "height");
    idx_coinbase = json_object_get(&doc, 0, "coinbasevalue");
    idx_wc = json_object_get(&doc, 0, "default_witness_commitment");
    idx_txs = json_object_get(&doc, 0, "transactions");

    if (idx_version < 0 || idx_prev < 0 || idx_curtime < 0 || idx_bits < 0 || idx_height < 0 || idx_coinbase < 0 || idx_txs < 0) {
        json_doc_free(&doc);
        free(result);
        return 0;
    }

    tpl->version = (int)token_to_ll(&doc, idx_version);
    tpl->curtime = (int)token_to_ll(&doc, idx_curtime);
    tpl->height = (int)token_to_ll(&doc, idx_height);
    tpl->coinbase_value = (uint64_t)token_to_ll(&doc, idx_coinbase);

    {
        char *prev = json_token_strdup(&doc, idx_prev);
        char *bits = json_token_strdup(&doc, idx_bits);
        if (prev == NULL || bits == NULL) {
            free(prev);
            free(bits);
            json_doc_free(&doc);
            free(result);
            return 0;
        }
        snprintf(tpl->previous_block_hash, sizeof(tpl->previous_block_hash), "%s", prev);
        snprintf(tpl->bits, sizeof(tpl->bits), "%s", bits);
        free(prev);
        free(bits);
    }

    if (idx_wc >= 0) {
        tpl->default_witness_commitment = json_token_strdup(&doc, idx_wc);
    }

    if (doc.tokens[idx_txs].type != JSMN_ARRAY) {
        json_doc_free(&doc);
        free(result);
        return 0;
    }

    tpl->tx_count = (size_t)doc.tokens[idx_txs].size;
    tpl->transactions = (TemplateTransaction *)calloc(tpl->tx_count, sizeof(TemplateTransaction));
    if (tpl->transactions == NULL && tpl->tx_count > 0) {
        json_doc_free(&doc);
        free(result);
        return 0;
    }

    for (i = 0; i < doc.tokens[idx_txs].size; i++) {
        int tx_idx = json_array_get(&doc, idx_txs, i);
        int txid_idx;
        int data_idx;
        char *txid;

        if (tx_idx < 0 || doc.tokens[tx_idx].type != JSMN_OBJECT) {
            json_doc_free(&doc);
            free(result);
            return 0;
        }

        txid_idx = json_object_get(&doc, tx_idx, "txid");
        data_idx = json_object_get(&doc, tx_idx, "data");
        if (txid_idx < 0 || data_idx < 0) {
            json_doc_free(&doc);
            free(result);
            return 0;
        }

        txid = json_token_strdup(&doc, txid_idx);
        tpl->transactions[i].data = json_token_strdup(&doc, data_idx);
        if (txid == NULL || tpl->transactions[i].data == NULL) {
            free(txid);
            json_doc_free(&doc);
            free(result);
            return 0;
        }

        snprintf(tpl->transactions[i].hash, sizeof(tpl->transactions[i].hash), "%s", txid);
        free(txid);
    }

    json_doc_free(&doc);
    free(result);
    return 1;
}

int rpc_ensure_witness_data(RpcClient *client, BlockTemplate *tpl) {
    size_t i;

    for (i = 0; i < tpl->tx_count; i++) {
        char *raw = NULL;
        if (rpc_get_raw_transaction(client, tpl->transactions[i].hash, &raw)) {
            free(tpl->transactions[i].data);
            tpl->transactions[i].data = raw;
        }
    }

    return 1;
}

int rpc_submit_block(RpcClient *client, const char *serialized_block) {
    char *params;
    char *result = NULL;
    size_t n;
    int accepted = 0;

    n = strlen(serialized_block) + 16;
    params = (char *)malloc(n);
    if (params == NULL) {
        return 0;
    }

    snprintf(params, n, "[\"%s\"]", serialized_block);

    if (rpc_call_result(client, "submitblock", params, &result) == 0) {
        free(params);
        return 0;
    }

    if (strcmp(result, "null") == 0) {
        accepted = 1;
    } else {
        fprintf(stderr, "[rpc] submitblock: %s\n", result);
    }

    free(result);
    free(params);
    return accepted;
}