/**
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0.
 */

#include <aws/common/logging.h>

#include <aws/common/file.h>
#include <aws/common/log_channel.h>
#include <aws/common/log_formatter.h>
#include <aws/common/log_writer.h>
#include <aws/common/mutex.h>
#include <aws/common/string.h>

#include <errno.h>
#include <stdarg.h>

#ifdef _MSC_VER
#    pragma warning(disable : 4204) /* non-constant aggregate initializer */
#endif

/*
 * Null logger implementation
 */
static enum aws_log_level s_null_logger_get_log_level(struct aws_logger *logger, aws_log_subject_t subject) {
    (void)logger;
    (void)subject;

    return AWS_LL_NONE;
}

static int s_null_logger_log(
    struct aws_logger *logger,
    enum aws_log_level log_level,
    aws_log_subject_t subject,
    const char *format,
    ...) {

    (void)logger;
    (void)log_level;
    (void)subject;
    (void)format;

    return AWS_OP_SUCCESS;
}

static void s_null_logger_clean_up(struct aws_logger *logger) {
    (void)logger;
}

static struct aws_logger_vtable s_null_vtable = {
    .get_log_level = s_null_logger_get_log_level,
    .log = s_null_logger_log,
    .clean_up = s_null_logger_clean_up,
};

static struct aws_logger s_null_logger = {
    .vtable = &s_null_vtable,
    .allocator = NULL,
    .p_impl = NULL,
};

/*
 * Pipeline logger implementation
 */
static void s_aws_logger_pipeline_owned_clean_up(struct aws_logger *logger) {
    struct aws_logger_pipeline *impl = logger->p_impl;

    AWS_ASSERT(impl->channel->vtable->clean_up != NULL);
    (impl->channel->vtable->clean_up)(impl->channel);

    AWS_ASSERT(impl->formatter->vtable->clean_up != NULL);
    (impl->formatter->vtable->clean_up)(impl->formatter);

    AWS_ASSERT(impl->writer->vtable->clean_up != NULL);
    (impl->writer->vtable->clean_up)(impl->writer);

    aws_mem_release(impl->allocator, impl->channel);
    aws_mem_release(impl->allocator, impl->formatter);
    aws_mem_release(impl->allocator, impl->writer);

    aws_mem_release(impl->allocator, impl);
}

/*
 * Pipeline logger implementation
 */
static int s_aws_logger_pipeline_log(
    struct aws_logger *logger,
    enum aws_log_level log_level,
    aws_log_subject_t subject,
    const char *format,
    ...) {
    va_list format_args;
    va_start(format_args, format);

    struct aws_logger_pipeline *impl = logger->p_impl;
    struct aws_string *output = NULL;

    AWS_ASSERT(impl->formatter->vtable->format != NULL);
    int result = (impl->formatter->vtable->format)(impl->formatter, &output, log_level, subject, format, format_args);

    va_end(format_args);

    if (result != AWS_OP_SUCCESS || output == NULL) {
        return AWS_OP_ERR;
    }

    AWS_ASSERT(impl->channel->vtable->send != NULL);
    if ((impl->channel->vtable->send)(impl->channel, output)) {
        /*
         * failure to send implies failure to transfer ownership
         */
        aws_string_destroy(output);
        return AWS_OP_ERR;
    }

    return AWS_OP_SUCCESS;
}

static enum aws_log_level s_aws_logger_pipeline_get_log_level(struct aws_logger *logger, aws_log_subject_t subject) {
    (void)subject;

    struct aws_logger_pipeline *impl = logger->p_impl;

    return (enum aws_log_level)aws_atomic_load_int(&impl->level);
}

static int s_aws_logger_pipeline_set_log_level(struct aws_logger *logger, enum aws_log_level level) {
    struct aws_logger_pipeline *impl = logger->p_impl;

    aws_atomic_store_int(&impl->level, (size_t)level);

    return AWS_OP_SUCCESS;
}

struct aws_logger_vtable g_pipeline_logger_owned_vtable = {
    .get_log_level = s_aws_logger_pipeline_get_log_level,
    .log = s_aws_logger_pipeline_log,
    .clean_up = s_aws_logger_pipeline_owned_clean_up,
    .set_log_level = s_aws_logger_pipeline_set_log_level,
};

int aws_logger_init_standard(
    struct aws_logger *logger,
    struct aws_allocator *allocator,
    struct aws_logger_standard_options *options) {

#ifdef ANDROID
    (void)options;
    extern int aws_logger_init_logcat(
        struct aws_logger *, struct aws_allocator *, struct aws_logger_standard_options *);
    return aws_logger_init_logcat(logger, allocator, options);
#endif

    struct aws_logger_pipeline *impl = aws_mem_calloc(allocator, 1, sizeof(struct aws_logger_pipeline));
    if (impl == NULL) {
        return AWS_OP_ERR;
    }

    struct aws_log_writer *writer = aws_mem_acquire(allocator, sizeof(struct aws_log_writer));
    if (writer == NULL) {
        goto on_allocate_writer_failure;
    }

    struct aws_log_writer_file_options file_writer_options = {
        .filename = options->filename,
        .file = options->file,
    };

    if (aws_log_writer_init_file(writer, allocator, &file_writer_options)) {
        goto on_init_writer_failure;
    }

    struct aws_log_formatter *formatter = aws_mem_acquire(allocator, sizeof(struct aws_log_formatter));
    if (formatter == NULL) {
        goto on_allocate_formatter_failure;
    }

    struct aws_log_formatter_standard_options formatter_options = {.date_format = AWS_DATE_FORMAT_ISO_8601};

    if (aws_log_formatter_init_default(formatter, allocator, &formatter_options)) {
        goto on_init_formatter_failure;
    }

    struct aws_log_channel *channel = aws_mem_acquire(allocator, sizeof(struct aws_log_channel));
    if (channel == NULL) {
        goto on_allocate_channel_failure;
    }

    if (aws_log_channel_init_background(channel, allocator, writer) == AWS_OP_SUCCESS) {
        impl->formatter = formatter;
        impl->channel = channel;
        impl->writer = writer;
        impl->allocator = allocator;
        aws_atomic_store_int(&impl->level, (size_t)options->level);

        logger->vtable = &g_pipeline_logger_owned_vtable;
        logger->allocator = allocator;
        logger->p_impl = impl;

        return AWS_OP_SUCCESS;
    }

    aws_mem_release(allocator, channel);

on_allocate_channel_failure:
    aws_log_formatter_clean_up(formatter);

on_init_formatter_failure:
    aws_mem_release(allocator, formatter);

on_allocate_formatter_failure:
    aws_log_writer_clean_up(writer);

on_init_writer_failure:
    aws_mem_release(allocator, writer);

on_allocate_writer_failure:
    aws_mem_release(allocator, impl);

    return AWS_OP_ERR;
}

/*
 * Pipeline logger implementation where all the components are externally owned.  No clean up
 * is done on the components.  Useful for tests where components are on the stack and often mocked.
 */
static void s_aws_pipeline_logger_unowned_clean_up(struct aws_logger *logger) {
    struct aws_logger_pipeline *impl = (struct aws_logger_pipeline *)logger->p_impl;

    aws_mem_release(impl->allocator, impl);
}

static struct aws_logger_vtable s_pipeline_logger_unowned_vtable = {
    .get_log_level = s_aws_logger_pipeline_get_log_level,
    .log = s_aws_logger_pipeline_log,
    .clean_up = s_aws_pipeline_logger_unowned_clean_up,
    .set_log_level = s_aws_logger_pipeline_set_log_level,
};

int aws_logger_init_from_external(
    struct aws_logger *logger,
    struct aws_allocator *allocator,
    struct aws_log_formatter *formatter,
    struct aws_log_channel *channel,
    struct aws_log_writer *writer,
    enum aws_log_level level) {

    struct aws_logger_pipeline *impl = aws_mem_acquire(allocator, sizeof(struct aws_logger_pipeline));

    if (impl == NULL) {
        return AWS_OP_ERR;
    }

    impl->formatter = formatter;
    impl->channel = channel;
    impl->writer = writer;
    impl->allocator = allocator;
    aws_atomic_store_int(&impl->level, (size_t)level);

    logger->vtable = &s_pipeline_logger_unowned_vtable;
    logger->allocator = allocator;
    logger->p_impl = impl;

    return AWS_OP_SUCCESS;
}

/*
 * Global API
 */
static struct aws_logger *s_root_logger_ptr = &s_null_logger;

void aws_logger_set(struct aws_logger *logger) {
    if (logger != NULL) {
        s_root_logger_ptr = logger;
    } else {
        s_root_logger_ptr = &s_null_logger;
    }
}

struct aws_logger *aws_logger_get(void) {
    return s_root_logger_ptr;
}

struct aws_logger *aws_logger_get_conditional(aws_log_subject_t subject, enum aws_log_level level) {
    if (s_root_logger_ptr == NULL) {
        return NULL;
    }

    if (s_root_logger_ptr->vtable->get_log_level(s_root_logger_ptr, subject) < level) {
        return NULL;
    }

    return s_root_logger_ptr;
}

void aws_logger_clean_up(struct aws_logger *logger) {
    AWS_ASSERT(logger->vtable->clean_up != NULL);

    logger->vtable->clean_up(logger);
}

static const char *s_log_level_strings[AWS_LL_COUNT] = {"NONE", "FATAL", "ERROR", "WARN", "INFO", "DEBUG", "TRACE"};

int aws_log_level_to_string(enum aws_log_level log_level, const char **level_string) {
    AWS_ERROR_PRECONDITION(log_level < AWS_LL_COUNT);

    if (level_string != NULL) {
        *level_string = s_log_level_strings[log_level];
    }

    return AWS_OP_SUCCESS;
}

int aws_string_to_log_level(const char *level_string, enum aws_log_level *log_level) {
    if (level_string != NULL && log_level != NULL) {
        size_t level_length = strlen(level_string);
        for (int i = 0; i < AWS_LL_COUNT; ++i) {
            if (aws_array_eq_c_str_ignore_case(level_string, level_length, s_log_level_strings[i])) {
                *log_level = i;
                return AWS_OP_SUCCESS;
            }
        }
    }

    aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
    return AWS_OP_ERR;
}

int aws_thread_id_t_to_string(aws_thread_id_t thread_id, char *buffer, size_t bufsz) {
    AWS_ERROR_PRECONDITION(AWS_THREAD_ID_T_REPR_BUFSZ == bufsz);
    AWS_ERROR_PRECONDITION(buffer && AWS_MEM_IS_WRITABLE(buffer, bufsz));
    size_t current_index = 0;
    unsigned char *bytes = (unsigned char *)&thread_id;
    for (size_t i = sizeof(aws_thread_id_t); i != 0; --i) {
        unsigned char c = bytes[i - 1];
        int written = snprintf(buffer + current_index, bufsz - current_index, "%02x", c);
        if (written < 0) {
            return AWS_OP_ERR;
        }
        current_index += written;
        if (bufsz <= current_index) {
            return AWS_OP_ERR;
        }
    }
    return AWS_OP_SUCCESS;
}

#define AWS_LOG_SUBJECT_SPACE_MASK (AWS_LOG_SUBJECT_STRIDE - 1)

static const uint32_t S_MAX_LOG_SUBJECT = AWS_LOG_SUBJECT_STRIDE * AWS_PACKAGE_SLOTS - 1;

static const struct aws_log_subject_info_list *volatile s_log_subject_slots[AWS_PACKAGE_SLOTS] = {0};

static const struct aws_log_subject_info *s_get_log_subject_info_by_id(aws_log_subject_t subject) {
    if (subject > S_MAX_LOG_SUBJECT) {
        return NULL;
    }

    uint32_t slot_index = subject >> AWS_LOG_SUBJECT_STRIDE_BITS;
    uint32_t subject_index = subject & AWS_LOG_SUBJECT_SPACE_MASK;

    const struct aws_log_subject_info_list *subject_slot = s_log_subject_slots[slot_index];

    if (!subject_slot || subject_index >= subject_slot->count) {
        return NULL;
    }

    return &subject_slot->subject_list[subject_index];
}

const char *aws_log_subject_name(aws_log_subject_t subject) {
    const struct aws_log_subject_info *subject_info = s_get_log_subject_info_by_id(subject);

    if (subject_info != NULL) {
        return subject_info->subject_name;
    }

    return "Unknown";
}

void aws_register_log_subject_info_list(struct aws_log_subject_info_list *log_subject_list) {
    /*
     * We're not so worried about these asserts being removed in an NDEBUG build
     * - we'll either segfault immediately (for the first two) or for the count
     * assert, the registration will be ineffective.
     */
    AWS_FATAL_ASSERT(log_subject_list);
    AWS_FATAL_ASSERT(log_subject_list->subject_list);
    AWS_FATAL_ASSERT(log_subject_list->count);

    const uint32_t min_range = log_subject_list->subject_list[0].subject_id;
    const uint32_t slot_index = min_range >> AWS_LOG_SUBJECT_STRIDE_BITS;

#if DEBUG_BUILD
    for (uint32_t i = 0; i < log_subject_list->count; ++i) {
        const struct aws_log_subject_info *info = &log_subject_list->subject_list[i];
        uint32_t expected_id = min_range + i;
        if (expected_id != info->subject_id) {
            fprintf(stderr, "\"%s\" is at wrong index in aws_log_subject_info[]\n", info->subject_name);
            AWS_FATAL_ASSERT(0);
        }
    }
#endif /* DEBUG_BUILD */

    if (slot_index >= AWS_PACKAGE_SLOTS) {
        /* This is an NDEBUG build apparently. Kill the process rather than
         * corrupting heap. */
        fprintf(stderr, "Bad log subject slot index 0x%016x\n", slot_index);
        abort();
    }

    s_log_subject_slots[slot_index] = log_subject_list;
}

void aws_unregister_log_subject_info_list(struct aws_log_subject_info_list *log_subject_list) {
    /*
     * We're not so worried about these asserts being removed in an NDEBUG build
     * - we'll either segfault immediately (for the first two) or for the count
     * assert, the registration will be ineffective.
     */
    AWS_FATAL_ASSERT(log_subject_list);
    AWS_FATAL_ASSERT(log_subject_list->subject_list);
    AWS_FATAL_ASSERT(log_subject_list->count);

    const uint32_t min_range = log_subject_list->subject_list[0].subject_id;
    const uint32_t slot_index = min_range >> AWS_LOG_SUBJECT_STRIDE_BITS;

    if (slot_index >= AWS_PACKAGE_SLOTS) {
        /* This is an NDEBUG build apparently. Kill the process rather than
         * corrupting heap. */
        fprintf(stderr, "Bad log subject slot index 0x%016x\n", slot_index);
        AWS_FATAL_ASSERT(false);
    }

    s_log_subject_slots[slot_index] = NULL;
}

/*
 * no alloc implementation
 */
struct aws_logger_noalloc {
    struct aws_atomic_var level;
    FILE *file;
    bool should_close;
    struct aws_mutex lock;
};

static enum aws_log_level s_noalloc_stderr_logger_get_log_level(struct aws_logger *logger, aws_log_subject_t subject) {
    (void)subject;

    struct aws_logger_noalloc *impl = logger->p_impl;
    return (enum aws_log_level)aws_atomic_load_int(&impl->level);
}

#define MAXIMUM_NO_ALLOC_LOG_LINE_SIZE 8192

static int s_noalloc_stderr_logger_log(
    struct aws_logger *logger,
    enum aws_log_level log_level,
    aws_log_subject_t subject,
    const char *format,
    ...) {

    char format_buffer[MAXIMUM_NO_ALLOC_LOG_LINE_SIZE];

    va_list format_args;
    va_start(format_args, format);

#ifdef _MSC_VER
#    pragma warning(push)
#    pragma warning(disable : 4221) /* allow struct member to reference format_buffer  */
#endif

    struct aws_logging_standard_formatting_data format_data = {
        .log_line_buffer = format_buffer,
        .total_length = MAXIMUM_NO_ALLOC_LOG_LINE_SIZE,
        .level = log_level,
        .subject_name = aws_log_subject_name(subject),
        .format = format,
        .date_format = AWS_DATE_FORMAT_ISO_8601,
        .allocator = logger->allocator,
        .amount_written = 0,
    };

#ifdef _MSC_VER
#    pragma warning(pop) /* disallow struct member to reference local value */
#endif

    int result = aws_format_standard_log_line(&format_data, format_args);

    va_end(format_args);

    if (result == AWS_OP_ERR) {
        return AWS_OP_ERR;
    }

    struct aws_logger_noalloc *impl = logger->p_impl;

    aws_mutex_lock(&impl->lock);

    int write_result = AWS_OP_SUCCESS;
    if (fwrite(format_buffer, 1, format_data.amount_written, impl->file) < format_data.amount_written) {
        int errno_value = errno; /* Always cache errno before potential side-effect */
        aws_translate_and_raise_io_error(errno_value);
        write_result = AWS_OP_ERR;
    }

    aws_mutex_unlock(&impl->lock);

    return write_result;
}

static void s_noalloc_stderr_logger_clean_up(struct aws_logger *logger) {
    if (logger == NULL) {
        return;
    }

    struct aws_logger_noalloc *impl = logger->p_impl;
    if (impl->should_close) {
        fclose(impl->file);
    }

    aws_mutex_clean_up(&impl->lock);

    aws_mem_release(logger->allocator, impl);
    AWS_ZERO_STRUCT(*logger);
}

int s_no_alloc_stderr_logger_set_log_level(struct aws_logger *logger, enum aws_log_level level) {
    struct aws_logger_noalloc *impl = logger->p_impl;

    aws_atomic_store_int(&impl->level, (size_t)level);

    return AWS_OP_SUCCESS;
}

static struct aws_logger_vtable s_noalloc_stderr_vtable = {
    .get_log_level = s_noalloc_stderr_logger_get_log_level,
    .log = s_noalloc_stderr_logger_log,
    .clean_up = s_noalloc_stderr_logger_clean_up,
    .set_log_level = s_no_alloc_stderr_logger_set_log_level,
};

int aws_logger_init_noalloc(
    struct aws_logger *logger,
    struct aws_allocator *allocator,
    struct aws_logger_standard_options *options) {

    struct aws_logger_noalloc *impl = aws_mem_calloc(allocator, 1, sizeof(struct aws_logger_noalloc));

    if (impl == NULL) {
        return AWS_OP_ERR;
    }

    aws_atomic_store_int(&impl->level, (size_t)options->level);

    if (options->file != NULL) {
        impl->file = options->file;
        impl->should_close = false;
    } else { /* _MSC_VER */
        if (options->filename != NULL) {
            impl->file = aws_fopen(options->filename, "w");
            if (!impl->file) {
                aws_mem_release(allocator, impl);
                return AWS_OP_ERR;
            }
            impl->should_close = true;
        } else {
            impl->file = stderr;
            impl->should_close = false;
        }
    }

    aws_mutex_init(&impl->lock);

    logger->vtable = &s_noalloc_stderr_vtable;
    logger->allocator = allocator;
    logger->p_impl = impl;

    return AWS_OP_SUCCESS;
}

int aws_logger_set_log_level(struct aws_logger *logger, enum aws_log_level level) {
    if (logger == NULL || logger->vtable == NULL) {
        return aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
    }

    if (logger->vtable->set_log_level == NULL) {
        return aws_raise_error(AWS_ERROR_UNIMPLEMENTED);
    }

    return logger->vtable->set_log_level(logger, level);
}