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

#include <yaml.h>

#include "probes.h"

/*
 * probes.yaml parser. Structure:
 *
 *   defaults:
 *     VAR: value
 *     ...
 *   profiles:
 *     name:
 *       VAR: value
 *     other: {}
 *
 * Parsed once and cached. See probes.h for semantics.
 */

#define DEFAULT_PROBES_FILE  "probes.yaml"

typedef struct { char *key; char *val; }            kv;
typedef struct { char *name; kv *vars; int nvars; } profile;

static kv      *g_def    = NULL;  static int g_ndef  = 0;
static profile *g_prof   = NULL;  static int g_nprof = 0;
static int      g_loaded = 0;
static char     g_source[1024] = "";

static char *xstrdup(const char *s)
{
    char  *p;
    size_t n;
    if (!s) return NULL;
    n = strlen(s) + 1;
    p = (char *)malloc(n);
    if (p) memcpy(p, s, n);
    return p;
}

static void add_kv(kv **arr, int *n, const char *k, const char *v)
{
    kv *t = (kv *)realloc(*arr, (*n + 1) * sizeof(kv));
    if (!t) { fprintf(stderr, "probes: out of memory\n"); return; }
    *arr = t;
    t[*n].key = xstrdup(k);
    t[*n].val = xstrdup(v);
    (*n)++;
}

static profile *add_profile(const char *name)
{
    profile *t = (profile *)realloc(g_prof, (g_nprof + 1) * sizeof(profile));
    if (!t) { fprintf(stderr, "probes: out of memory\n"); return NULL; }
    g_prof = t;
    g_prof[g_nprof].name  = xstrdup(name);
    g_prof[g_nprof].vars  = NULL;
    g_prof[g_nprof].nvars = 0;
    return &g_prof[g_nprof++];
}

/* Mapping context at each nesting depth. */
enum { C_NONE = 0, C_ROOT, C_DEFAULTS, C_PROFILES, C_PROFBODY };

#define MAX_DEPTH 16

static int load(const char *path)
{
    FILE          *f;
    yaml_parser_t  parser;
    yaml_event_t   ev;
    int            depth = 0, done = 0, rc = 0;
    int            ctx[MAX_DEPTH];
    char          *key[MAX_DEPTH];
    profile       *cur = NULL;
    int            i;

    f = fopen(path, "rb");
    if (!f) return -1;
    if (!yaml_parser_initialize(&parser)) { fclose(f); return -1; }
    yaml_parser_set_input_file(&parser, f);

    memset(ctx, 0, sizeof(ctx));
    memset(key, 0, sizeof(key));

    while (!done) {
        if (!yaml_parser_parse(&parser, &ev)) {
            fprintf(stderr, "probes: YAML parse error in %s: %s (line %lu)\n",
                    path, parser.problem ? parser.problem : "?",
                    (unsigned long)parser.problem_mark.line + 1);
            rc = -1;
            break;
        }

        switch (ev.type) {
        case YAML_MAPPING_START_EVENT: {
            int newc = C_NONE;
            if (depth == 0) {
                newc = C_ROOT;
            } else {
                int         c = ctx[depth];
                const char *k = key[depth];
                if (c == C_ROOT) {
                    if (k && !strcmp(k, "defaults"))      newc = C_DEFAULTS;
                    else if (k && !strcmp(k, "profiles")) newc = C_PROFILES;
                } else if (c == C_PROFILES) {
                    cur  = k ? add_profile(k) : NULL;
                    newc = C_PROFBODY;
                }
            }
            if (depth < MAX_DEPTH - 1) depth++;
            ctx[depth] = newc;
            free(key[depth]);
            key[depth] = NULL;
            break;
        }
        case YAML_MAPPING_END_EVENT:
            free(key[depth]);
            key[depth] = NULL;
            if (depth > 0) depth--;
            break;
        case YAML_SCALAR_EVENT: {
            const char *v = (const char *)ev.data.scalar.value;
            int         c = ctx[depth];
            if (c == C_DEFAULTS) {
                if (!key[depth]) { key[depth] = xstrdup(v); }
                else { add_kv(&g_def, &g_ndef, key[depth], v); free(key[depth]); key[depth] = NULL; }
            } else if (c == C_PROFBODY) {
                if (!key[depth]) { key[depth] = xstrdup(v); }
                else { if (cur) add_kv(&cur->vars, &cur->nvars, key[depth], v); free(key[depth]); key[depth] = NULL; }
            } else {
                /* C_ROOT / C_PROFILES: the scalar is a key/name whose
                 * value is the next mapping. */
                free(key[depth]);
                key[depth] = xstrdup(v);
            }
            break;
        }
        case YAML_STREAM_END_EVENT:
            done = 1;
            break;
        default:
            break;
        }
        yaml_event_delete(&ev);
    }

    for (i = 0; i < MAX_DEPTH; i++) free(key[i]);
    yaml_parser_delete(&parser);
    fclose(f);
    return rc;
}

static void ensure_loaded(void)
{
    const char *path;

    if (g_loaded) return;
    g_loaded = 1;

    path = getenv("BS_PROBES");
    if (!path || !*path) path = DEFAULT_PROBES_FILE;

    if (load(path) == 0 && (g_ndef > 0 || g_nprof > 0)) {
        strncpy(g_source, path, sizeof(g_source) - 1);
        g_source[sizeof(g_source) - 1] = '\0';
    }
    /* Silent when absent: probe profiles are optional. */
}

int probe_apply_defaults(probe_set_fn set, void *user)
{
    int i;
    ensure_loaded();
    for (i = 0; i < g_ndef; i++) set(user, g_def[i].key, g_def[i].val);
    return g_ndef;
}

int probe_apply_profile(const char *name, probe_set_fn set, void *user)
{
    int i, j;
    ensure_loaded();
    for (i = 0; i < g_nprof; i++) {
        if (!strcmp(g_prof[i].name, name)) {
            for (j = 0; j < g_prof[i].nvars; j++)
                set(user, g_prof[i].vars[j].key, g_prof[i].vars[j].val);
            return g_prof[i].nvars;
        }
    }
    return -1;
}

int probe_profile_count(void)
{
    ensure_loaded();
    return g_nprof;
}

const char *probe_profile_name(int index)
{
    ensure_loaded();
    return (index >= 0 && index < g_nprof) ? g_prof[index].name : NULL;
}

const char *probe_config_source(void)
{
    ensure_loaded();
    return g_source[0] ? g_source : NULL;
}