// SPDX-License-Identifier: GPL-2.0
#include <stdbool.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "metricgroup.h"
#include "debug.h"
#include "expr.h"
#include "expr-bison.h"
#include "expr-flex.h"
#include <linux/kernel.h>
#include <linux/zalloc.h>
#include <ctype.h>

#ifdef PARSER_DEBUG
extern int expr_debug;
#endif

struct expr_id_data {
        union {
                double val;
                struct {
                        double val;
                        const char *metric_name;
                        const char *metric_expr;
                } ref;
                struct expr_id  *parent;
        };

        enum {
                /* Holding a double value. */
                EXPR_ID_DATA__VALUE,
                /* Reference to another metric. */
                EXPR_ID_DATA__REF,
                /* A reference but the value has been computed. */
                EXPR_ID_DATA__REF_VALUE,
                /* A parent is remembered for the recursion check. */
                EXPR_ID_DATA__PARENT,
        } kind;
};

static size_t key_hash(const void *key, void *ctx __maybe_unused)
{
        const char *str = (const char *)key;
        size_t hash = 0;

        while (*str != '\0') {
                hash *= 31;
                hash += *str;
                str++;
        }
        return hash;
}

static bool key_equal(const void *key1, const void *key2,
                    void *ctx __maybe_unused)
{
        return !strcmp((const char *)key1, (const char *)key2);
}

/* Caller must make sure id is allocated */
int expr__add_id(struct expr_parse_ctx *ctx, const char *id)
{
        struct expr_id_data *data_ptr = NULL, *old_data = NULL;
        char *old_key = NULL;
        int ret;

        data_ptr = malloc(sizeof(*data_ptr));
        if (!data_ptr)
                return -ENOMEM;

        data_ptr->parent = ctx->parent;
        data_ptr->kind = EXPR_ID_DATA__PARENT;

        ret = hashmap__set(&ctx->ids, id, data_ptr,
                           (const void **)&old_key, (void **)&old_data);
        if (ret)
                free(data_ptr);
        free(old_key);
        free(old_data);
        return ret;
}

/* Caller must make sure id is allocated */
int expr__add_id_val(struct expr_parse_ctx *ctx, const char *id, double val)
{
        struct expr_id_data *data_ptr = NULL, *old_data = NULL;
        char *old_key = NULL;
        int ret;

        data_ptr = malloc(sizeof(*data_ptr));
        if (!data_ptr)
                return -ENOMEM;
        data_ptr->val = val;
        data_ptr->kind = EXPR_ID_DATA__VALUE;

        ret = hashmap__set(&ctx->ids, id, data_ptr,
                           (const void **)&old_key, (void **)&old_data);
        if (ret)
                free(data_ptr);
        free(old_key);
        free(old_data);
        return ret;
}

int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
{
        struct expr_id_data *data_ptr = NULL, *old_data = NULL;
        char *old_key = NULL;
        char *name, *p;
        int ret;

        data_ptr = zalloc(sizeof(*data_ptr));
        if (!data_ptr)
                return -ENOMEM;

        name = strdup(ref->metric_name);
        if (!name) {
                free(data_ptr);
                return -ENOMEM;
        }

        /*
         * The jevents tool converts all metric expressions
         * to lowercase, including metric references, hence
         * we need to add lowercase name for metric, so it's
         * properly found.
         */
        for (p = name; *p; p++)
                *p = tolower(*p);

        /*
         * Intentionally passing just const char pointers,
         * originally from 'struct pmu_event' object.
         * We don't need to change them, so there's no
         * need to create our own copy.
         */
        data_ptr->ref.metric_name = ref->metric_name;
        data_ptr->ref.metric_expr = ref->metric_expr;
        data_ptr->kind = EXPR_ID_DATA__REF;

        ret = hashmap__set(&ctx->ids, name, data_ptr,
                           (const void **)&old_key, (void **)&old_data);
        if (ret)
                free(data_ptr);

        pr_debug2("adding ref metric %s: %s\n",
                  ref->metric_name, ref->metric_expr);

        free(old_key);
        free(old_data);
        return ret;
}

int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
                 struct expr_id_data **data)
{
        return hashmap__find(&ctx->ids, id, (void **)data) ? 0 : -1;
}

int expr__resolve_id(struct expr_parse_ctx *ctx, const char *id,
                     struct expr_id_data **datap)
{
        struct expr_id_data *data;

        if (expr__get_id(ctx, id, datap) || !*datap) {
                pr_debug("%s not found\n", id);
                return -1;
        }

        data = *datap;

        switch (data->kind) {
        case EXPR_ID_DATA__VALUE:
                pr_debug2("lookup(%s): val %f\n", id, data->val);
                break;
        case EXPR_ID_DATA__PARENT:
                pr_debug2("lookup(%s): parent %s\n", id, data->parent->id);
                break;
        case EXPR_ID_DATA__REF:
                pr_debug2("lookup(%s): ref metric name %s\n", id,
                        data->ref.metric_name);
                pr_debug("processing metric: %s ENTRY\n", id);
                data->kind = EXPR_ID_DATA__REF_VALUE;
                if (expr__parse(&data->ref.val, ctx, data->ref.metric_expr, 1)) {
                        pr_debug("%s failed to count\n", id);
                        return -1;
                }
                pr_debug("processing metric: %s EXIT: %f\n", id, data->val);
                break;
        case EXPR_ID_DATA__REF_VALUE:
                pr_debug2("lookup(%s): ref val %f metric name %s\n", id,
                        data->ref.val, data->ref.metric_name);
                break;
        default:
                assert(0);  /* Unreachable. */
        }

        return 0;
}

void expr__del_id(struct expr_parse_ctx *ctx, const char *id)
{
        struct expr_id_data *old_val = NULL;
        char *old_key = NULL;

        hashmap__delete(&ctx->ids, id,
                        (const void **)&old_key, (void **)&old_val);
        free(old_key);
        free(old_val);
}

void expr__ctx_init(struct expr_parse_ctx *ctx)
{
        hashmap__init(&ctx->ids, key_hash, key_equal, NULL);
}

void expr__ctx_clear(struct expr_parse_ctx *ctx)
{
        struct hashmap_entry *cur;
        size_t bkt;

        hashmap__for_each_entry((&ctx->ids), cur, bkt) {
                free((char *)cur->key);
                free(cur->value);
        }
        hashmap__clear(&ctx->ids);
}

static int
__expr__parse(double *val, struct expr_parse_ctx *ctx, const char *expr,
              int start, int runtime)
{
        struct expr_scanner_ctx scanner_ctx = {
                .start_token = start,
                .runtime = runtime,
        };
        YY_BUFFER_STATE buffer;
        void *scanner;
        int ret;

        pr_debug2("parsing metric: %s\n", expr);

        ret = expr_lex_init_extra(&scanner_ctx, &scanner);
        if (ret)
                return ret;

        buffer = expr__scan_string(expr, scanner);

#ifdef PARSER_DEBUG
        expr_debug = 1;
        expr_set_debug(1, scanner);
#endif

        ret = expr_parse(val, ctx, scanner);

        expr__flush_buffer(buffer, scanner);
        expr__delete_buffer(buffer, scanner);
        expr_lex_destroy(scanner);
        return ret;
}

int expr__parse(double *final_val, struct expr_parse_ctx *ctx,
                const char *expr, int runtime)
{
        return __expr__parse(final_val, ctx, expr, EXPR_PARSE, runtime) ? -1 : 0;
}

int expr__find_other(const char *expr, const char *one,
                     struct expr_parse_ctx *ctx, int runtime)
{
        int ret = __expr__parse(NULL, ctx, expr, EXPR_OTHER, runtime);

        if (one)
                expr__del_id(ctx, one);

        return ret;
}

double expr_id_data__value(const struct expr_id_data *data)
{
        if (data->kind == EXPR_ID_DATA__VALUE)
                return data->val;
        assert(data->kind == EXPR_ID_DATA__REF_VALUE);
        return data->ref.val;
}

struct expr_id *expr_id_data__parent(struct expr_id_data *data)
{
        assert(data->kind == EXPR_ID_DATA__PARENT);
        return data->parent;
}