//! Bindings to the llama.cpp library.
//!
//! As llama.cpp is a very fast moving target, this crate does not attempt to create a stable API
//! with all the rust idioms. Instead it provided safe wrappers around nearly direct bindings to
//! llama.cpp. This makes it easier to keep up with the changes in llama.cpp, but does mean that
//! the API is not as nice as it could be.
//!
//! # Examples
//!
//! - [simple](https://github.com/utilityai/llama-cpp-rs/tree/main/examples/simple)
//!
//! # Feature Flags
//!
//! - `cuda` enables CUDA gpu support.
//! - `sampler` adds the [`context::sample::sampler`] struct for a more rusty way of sampling.
use std::ffi::{c_char, NulError};
use std::fmt::Debug;
use std::num::NonZeroI32;

use crate::llama_batch::BatchAddError;
use std::os::raw::c_int;
use std::path::PathBuf;
use std::string::FromUtf8Error;

pub mod context;
pub mod llama_backend;
pub mod llama_batch;
mod log;
pub mod model;
#[cfg(feature = "mtmd")]
pub mod mtmd;
pub mod sampling;
pub mod timing;
pub mod token;
pub mod token_type;

/// A failable result from a llama.cpp function.
pub type Result<T> = std::result::Result<T, LlamaCppError>;

/// All errors that can occur in the llama-cpp crate.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum LlamaCppError {
    /// The backend was already initialized. This can generally be ignored as initializing the backend
    /// is idempotent.
    #[error("BackendAlreadyInitialized")]
    BackendAlreadyInitialized,
    /// There was an error while get the chat template from model.
    #[error("{0}")]
    ChatTemplateError(#[from] ChatTemplateError),
    /// There was an error while decoding a batch.
    #[error("{0}")]
    DecodeError(#[from] DecodeError),
    /// There was an error while encoding a batch.
    #[error("{0}")]
    EncodeError(#[from] EncodeError),
    /// There was an error loading a model.
    #[error("{0}")]
    LlamaModelLoadError(#[from] LlamaModelLoadError),
    /// There was an error creating a new model context.
    #[error("{0}")]
    LlamaContextLoadError(#[from] LlamaContextLoadError),
    /// There was an error adding a token to a batch.
    #[error["{0}"]]
    BatchAddError(#[from] BatchAddError),
    /// see [`EmbeddingsError`]
    #[error(transparent)]
    EmbeddingError(#[from] EmbeddingsError),
    // See [`LlamaSamplerError`]
    /// Backend device not found
    #[error("Backend device {0} not found")]
    BackendDeviceNotFound(usize),
    /// Max devices exceeded
    #[error("Max devices exceeded. Max devices is {0}")]
    MaxDevicesExceeded(usize),
}

/// There was an error while getting the chat template from a model.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum ChatTemplateError {
    /// gguf has no chat template (by that name)
    #[error("chat template not found - returned null pointer")]
    MissingTemplate,

    /// chat template contained a null byte
    #[error("null byte in string {0}")]
    NullError(#[from] NulError),

    /// The chat template was not valid utf8.
    #[error(transparent)]
    Utf8Error(#[from] std::str::Utf8Error),
}

/// Failed fetching metadata value
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum MetaValError {
    /// The provided string contains an unexpected null-byte
    #[error("null byte in string {0}")]
    NullError(#[from] NulError),

    /// The returned data contains invalid UTF8 data
    #[error("FromUtf8Error {0}")]
    FromUtf8Error(#[from] FromUtf8Error),

    /// Got negative return value. This happens if the key or index queried does not exist.
    #[error("Negative return value. Likely due to a missing index or key. Got return value: {0}")]
    NegativeReturn(i32),
}

/// Failed to Load context
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum LlamaContextLoadError {
    /// llama.cpp returned null
    #[error("null reference from llama.cpp")]
    NullReturn,
}

/// Failed to decode a batch.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum DecodeError {
    /// No kv cache slot was available.
    #[error("Decode Error 1: NoKvCacheSlot")]
    NoKvCacheSlot,
    /// The number of tokens in the batch was 0.
    #[error("Decode Error -1: n_tokens == 0")]
    NTokensZero,
    /// An unknown error occurred.
    #[error("Decode Error {0}: unknown")]
    Unknown(c_int),
}

/// Failed to decode a batch.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum EncodeError {
    /// No kv cache slot was available.
    #[error("Encode Error 1: NoKvCacheSlot")]
    NoKvCacheSlot,
    /// The number of tokens in the batch was 0.
    #[error("Encode Error -1: n_tokens == 0")]
    NTokensZero,
    /// An unknown error occurred.
    #[error("Encode Error {0}: unknown")]
    Unknown(c_int),
}

/// When embedding related functions fail
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum EmbeddingsError {
    /// Embeddings weren't enabled in the context options
    #[error("Embeddings weren't enabled in the context options")]
    NotEnabled,
    /// Logits weren't enabled for the given token
    #[error("Logits were not enabled for the given token")]
    LogitsNotEnabled,
    /// The given sequence index exceeds the max sequence id
    #[error("Can't use sequence embeddings with a model supporting only LLAMA_POOLING_TYPE_NONE")]
    NonePoolType,
}

/// Errors that can occur when initializing a grammar sampler
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum GrammarError {
    /// The grammar root was not found in the grammar string
    #[error("Grammar root not found in grammar string")]
    RootNotFound,
    /// The trigger word contains null bytes
    #[error("Trigger word contains null bytes")]
    TriggerWordNullBytes,
    /// The grammar string or root contains null bytes
    #[error("Grammar string or root contains null bytes")]
    GrammarNullBytes,
    /// The grammar call returned null
    #[error("Grammar call returned null")]
    NullGrammar,
}

/// Decode a error from llama.cpp into a [`DecodeError`].
impl From<NonZeroI32> for DecodeError {
    fn from(value: NonZeroI32) -> Self {
        match value.get() {
            1 => DecodeError::NoKvCacheSlot,
            -1 => DecodeError::NTokensZero,
            i => DecodeError::Unknown(i),
        }
    }
}

/// Encode a error from llama.cpp into a [`EncodeError`].
impl From<NonZeroI32> for EncodeError {
    fn from(value: NonZeroI32) -> Self {
        match value.get() {
            1 => EncodeError::NoKvCacheSlot,
            -1 => EncodeError::NTokensZero,
            i => EncodeError::Unknown(i),
        }
    }
}

/// An error that can occur when loading a model.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum LlamaModelLoadError {
    /// There was a null byte in a provided string and thus it could not be converted to a C string.
    #[error("null byte in string {0}")]
    NullError(#[from] NulError),
    /// llama.cpp returned a nullptr - this could be many different causes.
    #[error("null result from llama cpp")]
    NullResult,
    /// Failed to convert the path to a rust str. This means the path was not valid unicode
    #[error("failed to convert path {0} to str")]
    PathToStrError(PathBuf),
}

/// An error that can occur when loading a model.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum LlamaLoraAdapterInitError {
    /// There was a null byte in a provided string and thus it could not be converted to a C string.
    #[error("null byte in string {0}")]
    NullError(#[from] NulError),
    /// llama.cpp returned a nullptr - this could be many different causes.
    #[error("null result from llama cpp")]
    NullResult,
    /// Failed to convert the path to a rust str. This means the path was not valid unicode
    #[error("failed to convert path {0} to str")]
    PathToStrError(PathBuf),
}

/// An error that can occur when loading a model.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum LlamaLoraAdapterSetError {
    /// llama.cpp returned a non-zero error code.
    #[error("error code from llama cpp")]
    ErrorResult(i32),
}

/// An error that can occur when loading a model.
#[derive(Debug, Eq, PartialEq, thiserror::Error)]
pub enum LlamaLoraAdapterRemoveError {
    /// llama.cpp returned a non-zero error code.
    #[error("error code from llama cpp")]
    ErrorResult(i32),
}

/// get the time (in microseconds) according to llama.cpp
/// ```
/// # use llama_cpp_2::llama_time_us;
/// # use llama_cpp_2::llama_backend::LlamaBackend;
/// let backend = LlamaBackend::init().unwrap();
/// let time = llama_time_us();
/// assert!(time > 0);
/// ```
#[must_use]
pub fn llama_time_us() -> i64 {
    unsafe { llama_cpp_sys_2::llama_time_us() }
}

/// get the max number of devices according to llama.cpp (this is generally cuda devices)
/// ```
/// # use llama_cpp_2::max_devices;
/// let max_devices = max_devices();
/// assert!(max_devices >= 0);
/// ```
#[must_use]
pub fn max_devices() -> usize {
    unsafe { llama_cpp_sys_2::llama_max_devices() }
}

/// is memory mapping supported according to llama.cpp
/// ```
/// # use llama_cpp_2::mmap_supported;
/// let mmap_supported = mmap_supported();
/// if mmap_supported {
///   println!("mmap_supported!");
/// }
/// ```
#[must_use]
pub fn mmap_supported() -> bool {
    unsafe { llama_cpp_sys_2::llama_supports_mmap() }
}

/// is memory locking supported according to llama.cpp
/// ```
/// # use llama_cpp_2::mlock_supported;
/// let mlock_supported = mlock_supported();
/// if mlock_supported {
///    println!("mlock_supported!");
/// }
/// ```
#[must_use]
pub fn mlock_supported() -> bool {
    unsafe { llama_cpp_sys_2::llama_supports_mlock() }
}

/// An error that can occur when converting a token to a string.
#[derive(Debug, thiserror::Error, Clone)]
#[non_exhaustive]
pub enum TokenToStringError {
    /// the token type was unknown
    #[error("Unknown Token Type")]
    UnknownTokenType,
    /// There was insufficient buffer space to convert the token to a string.
    #[error("Insufficient Buffer Space {0}")]
    InsufficientBufferSpace(c_int),
    /// The token was not valid utf8.
    #[error("FromUtf8Error {0}")]
    FromUtf8Error(#[from] FromUtf8Error),
}

/// Failed to convert a string to a token sequence.
#[derive(Debug, thiserror::Error)]
pub enum StringToTokenError {
    /// the string contained a null byte and thus could not be converted to a c string.
    #[error("{0}")]
    NulError(#[from] NulError),
    #[error("{0}")]
    /// Failed to convert a provided integer to a [`c_int`].
    CIntConversionError(#[from] std::num::TryFromIntError),
}

/// Failed to apply model chat template.
#[derive(Debug, thiserror::Error)]
pub enum NewLlamaChatMessageError {
    /// the string contained a null byte and thus could not be converted to a c string.
    #[error("{0}")]
    NulError(#[from] NulError),
}

/// Failed to apply model chat template.
#[derive(Debug, thiserror::Error)]
pub enum ApplyChatTemplateError {
    /// the string contained a null byte and thus could not be converted to a c string.
    #[error("{0}")]
    NulError(#[from] NulError),
    /// the string could not be converted to utf8.
    #[error("{0}")]
    FromUtf8Error(#[from] FromUtf8Error),
}

/// Get the time in microseconds according to ggml
///
/// ```
/// # use std::time::Duration;
/// # use llama_cpp_2::llama_backend::LlamaBackend;
/// let backend = LlamaBackend::init().unwrap();
/// use llama_cpp_2::ggml_time_us;
///
/// let start = ggml_time_us();
///
/// std::thread::sleep(Duration::from_micros(10));
///
/// let end = ggml_time_us();
///
/// let elapsed = end - start;
///
/// assert!(elapsed >= 10)
#[must_use]
pub fn ggml_time_us() -> i64 {
    unsafe { llama_cpp_sys_2::ggml_time_us() }
}

/// checks if mlock is supported
///
/// ```
/// # use llama_cpp_2::llama_supports_mlock;
///
/// if llama_supports_mlock() {
///   println!("mlock is supported!");
/// } else {
///   println!("mlock is not supported!");
/// }
/// ```
#[must_use]
pub fn llama_supports_mlock() -> bool {
    unsafe { llama_cpp_sys_2::llama_supports_mlock() }
}

/// Backend device type
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum LlamaBackendDeviceType {
    /// CPU device
    Cpu,
    /// ACCEL device
    Accelerator,
    /// GPU device
    Gpu,
    /// iGPU device
    IntegratedGpu,
    /// Unknown device type
    Unknown,
}

/// A ggml backend device
///
/// The index is can be used from `LlamaModelParams::with_devices` to select specific devices.
#[derive(Debug, Clone)]
pub struct LlamaBackendDevice {
    /// The index of the device
    ///
    /// The index is can be used from `LlamaModelParams::with_devices` to select specific devices.
    pub index: usize,
    /// The name of the device (e.g. "Vulkan0")
    pub name: String,
    /// A description of the device (e.g. "NVIDIA GeForce RTX 3080")
    pub description: String,
    /// The backend of the device (e.g. "Vulkan", "CUDA", "CPU")
    pub backend: String,
    /// Total memory of the device in bytes
    pub memory_total: usize,
    /// Free memory of the device in bytes
    pub memory_free: usize,
    /// Device type
    pub device_type: LlamaBackendDeviceType,
}

/// List ggml backend devices
#[must_use]
pub fn list_llama_ggml_backend_devices() -> Vec<LlamaBackendDevice> {
    let mut devices = Vec::new();
    for i in 0..unsafe { llama_cpp_sys_2::ggml_backend_dev_count() } {
        fn cstr_to_string(ptr: *const c_char) -> String {
            if ptr.is_null() {
                String::new()
            } else {
                unsafe { std::ffi::CStr::from_ptr(ptr) }
                    .to_string_lossy()
                    .to_string()
            }
        }
        let dev = unsafe { llama_cpp_sys_2::ggml_backend_dev_get(i) };
        let props = unsafe {
            let mut props = std::mem::zeroed();
            llama_cpp_sys_2::ggml_backend_dev_get_props(dev, &raw mut props);
            props
        };
        let name = cstr_to_string(props.name);
        let description = cstr_to_string(props.description);
        let backend = unsafe { llama_cpp_sys_2::ggml_backend_dev_backend_reg(dev) };
        let backend_name = unsafe { llama_cpp_sys_2::ggml_backend_reg_name(backend) };
        let backend = cstr_to_string(backend_name);
        let memory_total = props.memory_total;
        let memory_free = props.memory_free;
        let device_type = match props.type_ {
            llama_cpp_sys_2::GGML_BACKEND_DEVICE_TYPE_CPU => LlamaBackendDeviceType::Cpu,
            llama_cpp_sys_2::GGML_BACKEND_DEVICE_TYPE_ACCEL => LlamaBackendDeviceType::Accelerator,
            llama_cpp_sys_2::GGML_BACKEND_DEVICE_TYPE_GPU => LlamaBackendDeviceType::Gpu,
            llama_cpp_sys_2::GGML_BACKEND_DEVICE_TYPE_IGPU => LlamaBackendDeviceType::IntegratedGpu,
            _ => LlamaBackendDeviceType::Unknown,
        };
        devices.push(LlamaBackendDevice {
            index: i,
            name,
            description,
            backend,
            memory_total,
            memory_free,
            device_type,
        });
    }
    devices
}

/// Options to configure how llama.cpp logs are intercepted.
#[derive(Default, Debug, Clone)]
pub struct LogOptions {
    disabled: bool,
}

impl LogOptions {
    /// If enabled, logs are sent to tracing. If disabled, all logs are suppressed. Default is for
    /// logs to be sent to tracing.
    #[must_use]
    pub fn with_logs_enabled(mut self, enabled: bool) -> Self {
        self.disabled = !enabled;
        self
    }
}

extern "C" fn logs_to_trace(
    level: llama_cpp_sys_2::ggml_log_level,
    text: *const ::std::os::raw::c_char,
    data: *mut ::std::os::raw::c_void,
) {
    // In the "fast-path" (i.e. the vast majority of logs) we want to avoid needing to take the log state
    // lock at all. Similarly, we try to avoid any heap allocations within this function. This is accomplished
    // by being a dummy pass-through to tracing in the normal case of DEBUG/INFO/WARN/ERROR logs that are
    // newline terminated and limiting the slow-path of locks and/or heap allocations for other cases.
    use std::borrow::Borrow;

    let log_state = unsafe { &*(data as *const log::State) };

    if log_state.options.disabled {
        return;
    }

    // If the log level is disabled, we can just return early
    if !log_state.is_enabled_for_level(level) {
        log_state.update_previous_level_for_disabled_log(level);
        return;
    }

    let text = unsafe { std::ffi::CStr::from_ptr(text) };
    let text = text.to_string_lossy();
    let text: &str = text.borrow();

    // As best I can tell llama.cpp / ggml require all log format strings at call sites to have the '\n'.
    // If it's missing, it means that you expect more logs via CONT (or there's a typo in the codebase). To
    // distinguish typo from intentional support for CONT, we have to buffer until the next message comes in
    // to know how to flush it.

    if level == llama_cpp_sys_2::GGML_LOG_LEVEL_CONT {
        log_state.cont_buffered_log(text);
    } else if text.ends_with('\n') {
        log_state.emit_non_cont_line(level, text);
    } else {
        log_state.buffer_non_cont(level, text);
    }
}

/// Redirect llama.cpp logs into tracing.
pub fn send_logs_to_tracing(options: LogOptions) {
    // TODO: Reinitialize the state to support calling send_logs_to_tracing multiple times.

    // We set up separate log states for llama.cpp and ggml to make sure that CONT logs between the two
    // can't possibly interfere with each other. In other words, if llama.cpp emits a log without a trailing
    // newline and calls a GGML function, the logs won't be weirdly intermixed and instead we'll llama.cpp logs
    // will CONT previous llama.cpp logs and GGML logs will CONT previous ggml logs.
    let llama_heap_state = Box::as_ref(
        log::LLAMA_STATE
            .get_or_init(|| Box::new(log::State::new(log::Module::LlamaCpp, options.clone()))),
    ) as *const _;
    let ggml_heap_state = Box::as_ref(
        log::GGML_STATE.get_or_init(|| Box::new(log::State::new(log::Module::GGML, options))),
    ) as *const _;

    unsafe {
        // GGML has to be set after llama since setting llama sets ggml as well.
        llama_cpp_sys_2::llama_log_set(Some(logs_to_trace), llama_heap_state as *mut _);
        llama_cpp_sys_2::ggml_log_set(Some(logs_to_trace), ggml_heap_state as *mut _);
    }
}
