#include "hybbx/config.h"
#include "hybbx/limits.h"
#include "hybbx/util.h"

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define HYBBX_CONFIG_INITIAL_CAP 32

static char *hybbx_strdup(const char *s)
{
    size_t len;
    char *copy;

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

    len = strlen(s) + 1;
    copy = malloc(len);
    if (copy != NULL) {
        memcpy(copy, s, len);
    }
    return copy;
}

static char *trim_inplace(char *s)
{
    char *end;

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

    while (*s != '\0' && isspace((unsigned char)*s)) {
        s++;
    }

    if (*s == '\0') {
        return s;
    }

    end = s + strlen(s) - 1;
    while (end > s && isspace((unsigned char)*end)) {
        *end = '\0';
        end--;
    }

    return s;
}

static void strip_inline_comment_inplace(char *value)
{
    size_t i;
    int in_single = 0;
    int in_double = 0;

    if (value == NULL) {
        return;
    }

    for (i = 0; value[i] != '\0'; i++) {
        char c = value[i];

        if (!in_single && !in_double && (c == ';' || c == '#')) {
            value[i] = '\0';
            break;
        }

        if (!in_double && c == '\'') {
            in_single = !in_single;
        } else if (!in_single && c == '"') {
            in_double = !in_double;
        }
    }

    {
        char *end = value + strlen(value);

        while (end > value && isspace((unsigned char)*(end - 1))) {
            *--end = '\0';
        }
    }
}

static int is_comment_line(const char *line)
{
    const char *p = line;

    while (*p != '\0' && isspace((unsigned char)*p)) {
        p++;
    }

    return *p == ';' || *p == '#';
}

static hybbx_result_t append_entry(hybbx_config_t *config,
                                 const char *section,
                                 const char *key,
                                 const char *value)
{
    hybbx_config_entry_t *entry;
    hybbx_config_entry_t *grown;

    if (section == NULL || key == NULL || value == NULL) {
        return HYBBX_ERR_INVALID;
    }

    if (strlen(section) >= HYBBX_CONFIG_SECTION_MAX ||
        strlen(key) >= HYBBX_CONFIG_KEY_MAX ||
        strlen(value) >= HYBBX_CONFIG_VALUE_MAX) {
        return HYBBX_ERR_INVALID;
    }

    if (config->count == 0) {
        config->entries = malloc(HYBBX_CONFIG_INITIAL_CAP * sizeof(*config->entries));
        if (config->entries == NULL) {
            return HYBBX_ERR_NOMEM;
        }
    } else if ((config->count % HYBBX_CONFIG_INITIAL_CAP) == 0) {
        grown = realloc(config->entries,
                        (config->count + HYBBX_CONFIG_INITIAL_CAP) *
                            sizeof(*config->entries));
        if (grown == NULL) {
            return HYBBX_ERR_NOMEM;
        }
        config->entries = grown;
    }

    entry = &config->entries[config->count];
    entry->section = hybbx_strdup(section);
    entry->key = hybbx_strdup(key);
    entry->value = hybbx_strdup(value);

    if (entry->section == NULL || entry->key == NULL || entry->value == NULL) {
        free(entry->section);
        free(entry->key);
        free(entry->value);
        return HYBBX_ERR_NOMEM;
    }

    config->count++;
    return HYBBX_OK;
}

hybbx_result_t hybbx_config_load(hybbx_config_t *config, const char *path)
{
    FILE *fp;
    char line[HYBBX_CONFIG_LINE_MAX];
    char current_section[HYBBX_CONFIG_SECTION_MAX] = "";
    char *eq;
    char *key;
    char *value;

    if (config == NULL || path == NULL) {
        return HYBBX_ERR_INVALID;
    }

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

    fp = fopen(path, "r");
    if (fp == NULL) {
        return HYBBX_ERR_IO;
    }

    while (fgets(line, sizeof(line), fp) != NULL) {
        char *content;
        size_t len;

        len = strlen(line);
        if (len > 0 && line[len - 1] != '\n' &&
            len >= sizeof(line) - 1) {
            fclose(fp);
            hybbx_config_free(config);
            return HYBBX_ERR_INVALID;
        }

        content = trim_inplace(line);

        if (content[0] == '\0' || is_comment_line(content)) {
            continue;
        }

        if (content[0] == '[') {
            char *closing = strchr(content, ']');

            if (closing == NULL) {
                fclose(fp);
                hybbx_config_free(config);
                return HYBBX_ERR_INVALID;
            }

            *closing = '\0';
            strncpy(current_section, content + 1, sizeof(current_section) - 1);
            current_section[sizeof(current_section) - 1] = '\0';
            trim_inplace(current_section);
            continue;
        }

        if (current_section[0] == '\0') {
            fclose(fp);
            hybbx_config_free(config);
            return HYBBX_ERR_INVALID;
        }

        eq = strchr(content, '=');
        if (eq == NULL) {
            fclose(fp);
            hybbx_config_free(config);
            return HYBBX_ERR_INVALID;
        }

        *eq = '\0';
        key = trim_inplace(content);
        value = trim_inplace(eq + 1);
        strip_inline_comment_inplace(value);

        len = strlen(value);
        if (len >= 2 &&
            ((value[0] == '"' && value[len - 1] == '"') ||
             (value[0] == '\'' && value[len - 1] == '\''))) {
            value[len - 1] = '\0';
            value++;
        }

        if (append_entry(config, current_section, key, value) != HYBBX_OK) {
            fclose(fp);
            hybbx_config_free(config);
            return HYBBX_ERR_NOMEM;
        }
    }

    fclose(fp);
    return HYBBX_OK;
}

void hybbx_config_free(hybbx_config_t *config)
{
    size_t i;

    if (config == NULL) {
        return;
    }

    for (i = 0; i < config->count; i++) {
        free(config->entries[i].section);
        free(config->entries[i].key);
        free(config->entries[i].value);
    }

    free(config->entries);
    config->entries = NULL;
    config->count = 0;
}

const char *hybbx_config_get(const hybbx_config_t *config,
                             const char *section,
                             const char *key,
                             const char *default_value)
{
    size_t i;

    if (config == NULL || section == NULL || key == NULL) {
        return default_value;
    }

    for (i = 0; i < config->count; i++) {
        if (strcmp(config->entries[i].section, section) == 0 &&
            strcmp(config->entries[i].key, key) == 0) {
            return config->entries[i].value;
        }
    }

    return default_value;
}

int hybbx_config_get_bool(const hybbx_config_t *config,
                          const char *section,
                          const char *key,
                          int default_value)
{
    const char *value = hybbx_config_get(config, section, key, NULL);

    if (value == NULL) {
        return default_value;
    }

    return hybbx_parse_bool(value, default_value);
}

unsigned hybbx_config_get_uint(const hybbx_config_t *config,
                               const char *section,
                               const char *key,
                               unsigned default_value,
                               unsigned min_value,
                               unsigned max_value)
{
    const char *value;
    char *end;
    unsigned long parsed;

    value = hybbx_config_get(config, section, key, NULL);
    if (value == NULL || value[0] == '\0') {
        return default_value;
    }

    parsed = strtoul(value, &end, 10);
    if (end == value || *end != '\0') {
        return default_value;
    }

    if (parsed < min_value) {
        return min_value;
    }
    if (parsed > max_value) {
        return max_value;
    }

    return (unsigned)parsed;
}

static int config_section_has_keys(const hybbx_config_t *config,
                                   const char *section)
{
    size_t i;

    if (config == NULL || section == NULL) {
        return 0;
    }

    for (i = 0; i < config->count; i++) {
        const hybbx_config_entry_t *entry = &config->entries[i];

        if (strcmp(entry->section, section) != 0) {
            continue;
        }
        if (strcmp(entry->key, "enabled") == 0) {
            continue;
        }
        return 1;
    }

    return 0;
}

static int config_suffix_is_digits(const char *suffix)
{
    if (suffix == NULL || suffix[0] == '\0') {
        return 0;
    }

    while (*suffix != '\0') {
        if (!isdigit((unsigned char)*suffix)) {
            return 0;
        }
        suffix++;
    }

    return 1;
}

int hybbx_config_resolve_transport_section(const hybbx_config_t *config,
                                           const char *plugin_name,
                                           char *out_section,
                                           size_t out_size)
{
    char prefix[128];
    size_t prefix_len;
    size_t i;

    if (config == NULL || plugin_name == NULL || out_section == NULL ||
        out_size == 0) {
        return 0;
    }

    snprintf(prefix, sizeof(prefix), "transport.%s", plugin_name);
    if (config_section_has_keys(config, prefix)) {
        hybbx_strlcpy(out_section, prefix, out_size);
        return 1;
    }

    prefix_len = strlen(prefix);
    for (i = 0; i < config->count; i++) {
        const char *sec = config->entries[i].section;
        const char *suffix;

        if (sec == NULL || strncmp(sec, prefix, prefix_len) != 0) {
            continue;
        }

        suffix = sec + prefix_len;
        if (!config_suffix_is_digits(suffix)) {
            continue;
        }
        if (!config_section_has_keys(config, sec)) {
            continue;
        }

        hybbx_strlcpy(out_section, sec, out_size);
        return 1;
    }

    hybbx_strlcpy(out_section, prefix, out_size);
    return 0;
}

char *hybbx_config_format_section(const hybbx_config_t *config,
                                  const char *section)
{
    size_t i;
    size_t cap = 64;
    size_t len = 0;
    char *out;
    int first = 1;

    if (config == NULL || section == NULL) {
        return NULL;
    }

    out = malloc(cap);
    if (out == NULL) {
        return NULL;
    }
    out[0] = '\0';

    for (i = 0; i < config->count; i++) {
        const hybbx_config_entry_t *entry = &config->entries[i];
        size_t need;

        if (strcmp(entry->section, section) != 0) {
            continue;
        }

        if (strcmp(entry->key, "enabled") == 0) {
            continue;
        }

        need = strlen(entry->key) + strlen(entry->value) + 2;
        if (!first) {
            need++;
        }

        if (len + need + 1 > cap) {
            char *grown;

            while (len + need + 1 > cap) {
                cap *= 2;
            }
            grown = realloc(out, cap);
            if (grown == NULL) {
                free(out);
                return NULL;
            }
            out = grown;
        }

        if (!first) {
            out[len++] = ';';
            out[len] = '\0';
        }

        len += (size_t)snprintf(out + len, cap - len, "%s=%s",
                                entry->key, entry->value);
        first = 0;
    }

    return out;
}

typedef struct format_transport_ctx {
    const hybbx_config_t *config;
    const char *prefix;
    size_t prefix_len;
    char **sections;
    size_t count;
    size_t cap;
} format_transport_ctx_t;

static int format_transport_section_seen(format_transport_ctx_t *ctx,
                                         const char *section)
{
    size_t i;

    for (i = 0; i < ctx->count; i++) {
        if (strcmp(ctx->sections[i], section) == 0) {
            return 1;
        }
    }
    return 0;
}

static hybbx_result_t format_transport_section_add(format_transport_ctx_t *ctx,
                                                 const char *section)
{
    char *copy;

    if (format_transport_section_seen(ctx, section)) {
        return HYBBX_OK;
    }

    if (ctx->count >= ctx->cap) {
        size_t new_cap = ctx->cap == 0 ? 4 : ctx->cap * 2;
        char **grown = realloc(ctx->sections, new_cap * sizeof(*grown));

        if (grown == NULL) {
            return HYBBX_ERR_NOMEM;
        }
        ctx->sections = grown;
        ctx->cap = new_cap;
    }

    copy = hybbx_strdup(section);
    if (copy == NULL) {
        return HYBBX_ERR_NOMEM;
    }

    ctx->sections[ctx->count++] = copy;
    return HYBBX_OK;
}

char *hybbx_config_format_transport_sections(const hybbx_config_t *config,
                                             const char *plugin_name)
{
    format_transport_ctx_t ctx;
    char prefix[128];
    size_t i;
    size_t len = 0;
    size_t cap = 64;
    char *out;
    hybbx_result_t rc;

    if (config == NULL || plugin_name == NULL) {
        return NULL;
    }

    memset(&ctx, 0, sizeof(ctx));
    ctx.config = config;
    snprintf(prefix, sizeof(prefix), "transport.%s", plugin_name);
    ctx.prefix = prefix;
    ctx.prefix_len = strlen(prefix);

    if (config_section_has_keys(config, prefix)) {
        rc = format_transport_section_add(&ctx, prefix);
        if (rc != HYBBX_OK) {
            goto fail;
        }
    }

    for (i = 0; i < config->count; i++) {
        const char *sec = config->entries[i].section;
        const char *suffix;

        if (sec == NULL || strncmp(sec, prefix, ctx.prefix_len) != 0) {
            continue;
        }

        suffix = sec + ctx.prefix_len;
        if (!config_suffix_is_digits(suffix)) {
            continue;
        }
        if (!config_section_has_keys(config, sec)) {
            continue;
        }

        rc = format_transport_section_add(&ctx, sec);
        if (rc != HYBBX_OK) {
            goto fail;
        }
    }

    if (ctx.count == 0) {
        for (i = 0; i < ctx.count; i++) {
            free(ctx.sections[i]);
        }
        free(ctx.sections);
        return hybbx_config_format_section(config, prefix);
    }

    out = malloc(cap);
    if (out == NULL) {
        rc = HYBBX_ERR_NOMEM;
        goto fail;
    }
    out[0] = '\0';

    for (i = 0; i < ctx.count; i++) {
        char *section_cfg = hybbx_config_format_section(config, ctx.sections[i]);
        size_t part_len;

        if (section_cfg == NULL) {
            free(out);
            rc = HYBBX_ERR_NOMEM;
            goto fail;
        }

        part_len = strlen(section_cfg);
        if (len > 0) {
            if (len + 1 + part_len + 1 > cap) {
                while (len + 1 + part_len + 1 > cap) {
                    cap *= 2;
                }
                {
                    char *grown = realloc(out, cap);

                    if (grown == NULL) {
                        free(section_cfg);
                        free(out);
                        rc = HYBBX_ERR_NOMEM;
                        goto fail;
                    }
                    out = grown;
                }
            }
            out[len++] = HYBBX_PACKET_RADIO_INSTANCE_SEP;
            out[len] = '\0';
        }

        if (len + part_len + 1 > cap) {
            while (len + part_len + 1 > cap) {
                cap *= 2;
            }
            {
                char *grown = realloc(out, cap);

                if (grown == NULL) {
                    free(section_cfg);
                    free(out);
                    rc = HYBBX_ERR_NOMEM;
                    goto fail;
                }
                out = grown;
            }
        }

        memcpy(out + len, section_cfg, part_len + 1);
        len += part_len;
        free(section_cfg);
    }

    for (i = 0; i < ctx.count; i++) {
        free(ctx.sections[i]);
    }
    free(ctx.sections);
    return out;

fail:
    for (i = 0; i < ctx.count; i++) {
        free(ctx.sections[i]);
    }
    free(ctx.sections);
    return NULL;
}

char *hybbx_config_prepend_packet_radio_max25(const hybbx_config_t *config,
                                              const char *body)
{
    char prefix[HYBBX_CONFIG_VALUE_MAX * 2];
    char *out;
    size_t prefix_len;
    size_t body_len;
    int check;

    if (config == NULL) {
        return body != NULL ? hybbx_strdup(body) : NULL;
    }

    if (body == NULL || body[0] == '\0') {
        return hybbx_strdup(body != NULL ? body : "");
    }

    check = hybbx_config_get_bool(config, "max25", "check", 1);
    snprintf(prefix, sizeof(prefix),
             "max25_check=%s;max25_host=%s;max25_port=%u;max25_timeout_ms=%u",
             check ? "yes" : "no",
             hybbx_config_get(config, "max25", "host", "127.0.0.1"),
             hybbx_config_get_uint(config, "max25", "port",
                                   HYBBX_MAX25_DEFAULT_PORT, 1u, 65535u),
             hybbx_config_get_uint(config, "max25", "timeout_ms",
                                   HYBBX_MAX25_PROBE_TIMEOUT_MS,
                                   100u, 60000u));

    if (body == NULL || body[0] == '\0') {
        return hybbx_strdup(prefix);
    }

    prefix_len = strlen(prefix);
    body_len = strlen(body);
    out = malloc(prefix_len + 1u + body_len + 1u);
    if (out == NULL) {
        return NULL;
    }

    memcpy(out, prefix, prefix_len);
    out[prefix_len] = HYBBX_PACKET_RADIO_INSTANCE_SEP;
    memcpy(out + prefix_len + 1u, body, body_len + 1u);
    return out;
}

char *hybbx_config_format_packet_radio_start(const hybbx_config_t *config)
{
    char *body;

    body = hybbx_config_format_transport_sections(config, "packet_radio");
    if (body == NULL) {
        return NULL;
    }

    {
        char *out = hybbx_config_prepend_packet_radio_max25(config, body);

        free(body);
        return out;
    }
}

char *hybbx_config_format_baycom_start(const hybbx_config_t *config)
{
    char *body;

    body = hybbx_config_format_transport_sections(config, "baycom");
    if (body == NULL) {
        return NULL;
    }

    {
        char *out = hybbx_config_prepend_packet_radio_max25(config, body);

        free(body);
        return out;
    }
}

void hybbx_config_foreach(const hybbx_config_t *config,
                          hybbx_config_iter_fn fn, void *ctx)
{
    size_t i;

    if (config == NULL || fn == NULL) {
        return;
    }

    for (i = 0; i < config->count; i++) {
        const hybbx_config_entry_t *entry = &config->entries[i];

        fn(entry->section, entry->key, entry->value, ctx);
    }
}

void hybbx_config_foreach_section(const hybbx_config_t *config,
                                  hybbx_config_section_iter_fn fn, void *ctx)
{
    size_t i;

    if (config == NULL || fn == NULL) {
        return;
    }

    for (i = 0; i < config->count; i++) {
        const char *section = config->entries[i].section;
        size_t j;
        int seen = 0;

        for (j = 0; j < i; j++) {
            if (strcmp(config->entries[j].section, section) == 0) {
                seen = 1;
                break;
            }
        }

        if (!seen) {
            fn(section, ctx);
        }
    }
}

hybbx_result_t hybbx_config_set(hybbx_config_t *config,
                               const char *section,
                               const char *key,
                               const char *value)
{
    size_t i;

    if (config == NULL || section == NULL || key == NULL || value == NULL) {
        return HYBBX_ERR_INVALID;
    }

    for (i = 0; i < config->count; i++) {
        if (strcmp(config->entries[i].section, section) == 0 &&
            strcmp(config->entries[i].key, key) == 0) {
            char *copy = hybbx_strdup(value);

            if (copy == NULL) {
                return HYBBX_ERR_NOMEM;
            }
            free(config->entries[i].value);
            config->entries[i].value = copy;
            return HYBBX_OK;
        }
    }

    return append_entry(config, section, key, value);
}

void hybbx_config_remove_section(hybbx_config_t *config, const char *section)
{
    size_t i;

    if (config == NULL || section == NULL) {
        return;
    }

    i = 0;
    while (i < config->count) {
        if (strcmp(config->entries[i].section, section) == 0) {
            free(config->entries[i].section);
            free(config->entries[i].key);
            free(config->entries[i].value);
            if (i + 1 < config->count) {
                memmove(&config->entries[i], &config->entries[i + 1],
                        (config->count - i - 1) * sizeof(config->entries[i]));
            }
            config->count--;
        } else {
            i++;
        }
    }
}

hybbx_result_t hybbx_config_save(const hybbx_config_t *config,
                                 const char *path)
{
    FILE *fp;
    size_t i;
    const char *current = NULL;

    if (config == NULL || path == NULL) {
        return HYBBX_ERR_INVALID;
    }

    fp = fopen(path, "w");
    if (fp == NULL) {
        return HYBBX_ERR_IO;
    }

    for (i = 0; i < config->count; i++) {
        const hybbx_config_entry_t *entry = &config->entries[i];

        if (current == NULL || strcmp(current, entry->section) != 0) {
            if (current != NULL) {
                fputc('\n', fp);
            }
            fprintf(fp, "[%s]\n", entry->section);
            current = entry->section;
        }
        fprintf(fp, "%s = %s\n", entry->key, entry->value);
    }

    fclose(fp);
    return HYBBX_OK;
}