/* SPDX-License-Identifier: GPL-3.0-only */
/* Persistent HTTPS identity; authentication belongs to the user database. */

#pragma once

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#include "esp_err.h"

#ifdef __cplusplus
extern "C" {
#endif

#define WEB_SECURITY_NVS_NAMESPACE "web_sec"
#define WEB_SECURITY_NVS_BLOB_KEY "material"


#define WEB_SECURITY_PRIVATE_KEY_DER_CAPACITY 256U
#define WEB_SECURITY_CERTIFICATE_DER_CAPACITY 1024U
#define WEB_SECURITY_SHA256_LENGTH 32U
#define WEB_SECURITY_COMMON_NAME_CAPACITY 32U
#define WEB_SECURITY_DNS_NAME_CAPACITY 40U

#define WEB_SECURITY_CERT_NOT_BEFORE "20250101000000"
#define WEB_SECURITY_CERT_NOT_AFTER "20491231235959"

typedef enum {
    WEB_SECURITY_LOAD_STORED = 0,
    WEB_SECURITY_LOAD_GENERATED_MISSING = 1,
    WEB_SECURITY_LOAD_MIGRATED_V1 = 2,
} web_security_load_result_t;


typedef struct {
    uint32_t material_generation;
    uint8_t sha256_fingerprint[WEB_SECURITY_SHA256_LENGTH];
    char common_name[WEB_SECURITY_COMMON_NAME_CAPACITY];
    char dns_name[WEB_SECURITY_DNS_NAME_CAPACITY];
    uint8_t ipv4_address[4];
    char not_before[sizeof(WEB_SECURITY_CERT_NOT_BEFORE)];
    char not_after[sizeof(WEB_SECURITY_CERT_NOT_AFTER)];
} web_security_certificate_metadata_t;

/*
 * NVS must already be initialized. Missing TLS material is generated and saved.
 * Valid v1 material is migrated to certificate-only v2 before publication,
 * preserving exact TLS identity and generation. Replacement is logical NVS
 * deletion of legacy fields, not secure flash erasure. Migration failure never
 * triggers regeneration or fallback overwrite;
 * an existing wrong-version blob returns ESP_ERR_INVALID_VERSION, while any
 * malformed or cryptographically inconsistent blob returns
 * ESP_ERR_INVALID_RESPONSE and is never overwritten. Call before radio startup
 * so secure_random_init() can seed from the pre-radio entropy source.
 */
esp_err_t web_security_init(web_security_load_result_t *load_result);

/*
 * Query with both outputs NULL/capacities zero. Certificate and key are copied
 * under one lock so a concurrent rotation can never produce a mismatched pair.
 */
esp_err_t web_security_copy_tls_material(
    uint8_t *certificate, size_t certificate_capacity,
    size_t *certificate_length,
    uint8_t *private_key, size_t private_key_capacity,
    size_t *private_key_length);


esp_err_t web_security_get_certificate_metadata(
    web_security_certificate_metadata_t *metadata);

typedef struct {
    uint32_t generation;
    uint8_t fingerprint[WEB_SECURITY_SHA256_LENGTH];
    bool busy;
} web_security_identity_snapshot_t;

/* Zero-wait public metadata only; never returns DER or private material. */
esp_err_t web_security_get_identity_snapshot(web_security_identity_snapshot_t *snapshot);

/* Internal owner transaction shared with canonical mutations. Tokens never reuse.
 * Reserve before crypto; retain through service restart. No lock stays held.
 * Zero expected_generation selects canonical CLI semantics; reset permits recovery.
 * Only the reserving owner may replace once and release its token. */
esp_err_t web_security_reserve_identity(uint32_t expected_generation, bool reset, uint32_t *token);
esp_err_t web_security_replace_reserved(uint32_t token);
void web_security_release_identity(uint32_t token);

/* Mutations become visible only after a complete blob has committed to NVS. */

esp_err_t web_security_rotate_certificate(void);

/* TLS ONLY: explicitly replaces missing, valid, or incompatible material.
 * Generation increments from live state, or starts at one if unavailable.
 * No user database mutation. */
esp_err_t web_security_reset_all(void);

#ifdef __cplusplus
}
#endif