//! 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::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`]
}

/// 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,
}

/// 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() }
}

/// 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.
    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 _);
    }
}
