// SPDX-FileCopyrightText: Copyright (c) 2024-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

use super::Result;
use derive_builder::Builder;
use figment::{
    providers::{Env, Format, Serialized, Toml},
    Figment,
};
use serde::{Deserialize, Serialize};
use std::fmt;
use validator::Validate;

/// Default HTTP server host
const DEFAULT_HTTP_SERVER_HOST: &str = "0.0.0.0";

/// Default HTTP server port
const DEFAULT_HTTP_SERVER_PORT: u16 = 9090;

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct WorkerConfig {
    /// Grace shutdown period for http-service.
    pub graceful_shutdown_timeout: u64,
}

impl WorkerConfig {
    /// Instantiates and reads server configurations from appropriate sources.
    /// Panics on invalid configuration.
    pub fn from_settings() -> Self {
        // All calls should be global and thread safe.
        Figment::new()
            .merge(Serialized::defaults(Self::default()))
            .merge(Env::prefixed("DYN_WORKER_"))
            .extract()
            .unwrap() // safety: Called on startup, so panic is reasonable
    }
}

impl Default for WorkerConfig {
    fn default() -> Self {
        WorkerConfig {
            graceful_shutdown_timeout: if cfg!(debug_assertions) {
                1 // Debug build: 1 second
            } else {
                30 // Release build: 30 seconds
            },
        }
    }
}

/// Runtime configuration
/// Defines the configuration for Tokio runtimes
#[derive(Serialize, Deserialize, Validate, Debug, Builder, Clone)]
#[builder(build_fn(private, name = "build_internal"), derive(Debug, Serialize))]
pub struct RuntimeConfig {
    /// Number of async worker threads
    /// If set to 1, the runtime will run in single-threaded mode
    /// Set this at runtime with environment variable DYN_RUNTIME_NUM_WORKER_THREADS. Defaults to
    /// number of cores.
    #[validate(range(min = 1))]
    #[builder_field_attr(serde(skip_serializing_if = "Option::is_none"))]
    pub num_worker_threads: Option<usize>,

    /// Maximum number of blocking threads
    /// Blocking threads are used for blocking operations, this value must be greater than 0.
    /// Set this at runtime with environment variable DYN_RUNTIME_MAX_BLOCKING_THREADS. Defaults to
    /// 512.
    #[validate(range(min = 1))]
    #[builder(default = "512")]
    #[builder_field_attr(serde(skip_serializing_if = "Option::is_none"))]
    pub max_blocking_threads: usize,

    /// HTTP server host for health and metrics endpoints
    /// Set this at runtime with environment variable DYN_RUNTIME_HTTP_SERVER_HOST
    #[builder(default = "DEFAULT_HTTP_SERVER_HOST.to_string()")]
    #[builder_field_attr(serde(skip_serializing_if = "Option::is_none"))]
    pub http_server_host: String,

    /// HTTP server port for health and metrics endpoints
    /// If set to 0, the system will assign a random available port
    /// Set this at runtime with environment variable DYN_RUNTIME_HTTP_SERVER_PORT
    #[builder(default = "DEFAULT_HTTP_SERVER_PORT")]
    #[builder_field_attr(serde(skip_serializing_if = "Option::is_none"))]
    pub http_server_port: u16,

    /// Health and metrics HTTP server enabled
    /// Set this at runtime with environment variable DYN_RUNTIME_HTTP_ENABLED
    #[builder(default = "false")]
    #[builder_field_attr(serde(skip_serializing_if = "Option::is_none"))]
    pub http_enabled: bool,
}

impl fmt::Display for RuntimeConfig {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // If None, it defaults to "number of cores", so we indicate that.
        match self.num_worker_threads {
            Some(val) => write!(f, "num_worker_threads={val}, ")?,
            None => write!(f, "num_worker_threads=default (num_cores), ")?,
        }

        write!(f, "max_blocking_threads={}, ", self.max_blocking_threads)?;
        write!(f, "http_server_host={}, ", self.http_server_host)?;
        write!(f, "http_server_port={}, ", self.http_server_port)?;
        write!(f, "http_enabled={}", self.http_enabled)?;

        Ok(())
    }
}

impl RuntimeConfig {
    pub fn builder() -> RuntimeConfigBuilder {
        RuntimeConfigBuilder::default()
    }

    pub(crate) fn figment() -> Figment {
        Figment::new()
            .merge(Serialized::defaults(RuntimeConfig::default()))
            .merge(Toml::file("/opt/dynamo/defaults/runtime.toml"))
            .merge(Toml::file("/opt/dynamo/etc/runtime.toml"))
            .merge(Env::prefixed("DYN_RUNTIME_").filter_map(|k| {
                let full_key = format!("DYN_RUNTIME_{}", k.as_str());
                // filters out empty environment variables
                match std::env::var(&full_key) {
                    Ok(v) if !v.is_empty() => Some(k.into()),
                    _ => None,
                }
            }))
    }

    /// Load the runtime configuration from the environment and configuration files
    /// Configuration is priorities in the following order, where the last has the lowest priority:
    /// 1. Environment variables (top priority)
    ///    TO DO: Add documentation for configuration files. Paths should be configurable.
    /// 2. /opt/dynamo/etc/runtime.toml
    /// 3. /opt/dynamo/defaults/runtime.toml (lowest priority)
    ///
    /// Environment variables are prefixed with `DYN_RUNTIME_`
    pub fn from_settings() -> Result<RuntimeConfig> {
        let config: RuntimeConfig = Self::figment().extract()?;
        config.validate()?;
        Ok(config)
    }

    /// Check if HTTP server should be enabled
    /// HTTP server is enabled by default, but can be disabled by setting DYN_RUNTIME_HTTP_ENABLED to false
    /// If a port is explicitly provided, HTTP server will be enabled regardless
    pub fn http_server_enabled(&self) -> bool {
        self.http_enabled
    }

    pub fn single_threaded() -> Self {
        RuntimeConfig {
            num_worker_threads: Some(1),
            max_blocking_threads: 1,
            http_server_host: DEFAULT_HTTP_SERVER_HOST.to_string(),
            http_server_port: DEFAULT_HTTP_SERVER_PORT,
            http_enabled: false,
        }
    }

    /// Create a new default runtime configuration
    pub(crate) fn create_runtime(&self) -> std::io::Result<tokio::runtime::Runtime> {
        tokio::runtime::Builder::new_multi_thread()
            .worker_threads(
                self.num_worker_threads
                    .unwrap_or_else(|| std::thread::available_parallelism().unwrap().get()),
            )
            .max_blocking_threads(self.max_blocking_threads)
            .enable_all()
            .build()
    }
}

impl Default for RuntimeConfig {
    fn default() -> Self {
        let num_cores = std::thread::available_parallelism().unwrap().get();
        Self {
            num_worker_threads: Some(num_cores),
            max_blocking_threads: num_cores,
            http_server_host: DEFAULT_HTTP_SERVER_HOST.to_string(),
            http_server_port: DEFAULT_HTTP_SERVER_PORT,
            http_enabled: false,
        }
    }
}

impl RuntimeConfigBuilder {
    /// Build and validate the runtime configuration
    pub fn build(&self) -> Result<RuntimeConfig> {
        let config = self.build_internal()?;
        config.validate()?;
        Ok(config)
    }
}

/// Check if a string is truthy
/// This will be used to evaluate environment variables or any other subjective
/// configuration parameters that can be set by the user that should be evaluated
/// as a boolean value.
pub fn is_truthy(val: &str) -> bool {
    matches!(val.to_lowercase().as_str(), "1" | "true" | "on" | "yes")
}

/// Check if a string is falsey
/// This will be used to evaluate environment variables or any other subjective
/// configuration parameters that can be set by the user that should be evaluated
/// as a boolean value (opposite of is_truthy).
pub fn is_falsey(val: &str) -> bool {
    matches!(val.to_lowercase().as_str(), "0" | "false" | "off" | "no")
}

/// Check if an environment variable is truthy
pub fn env_is_truthy(env: &str) -> bool {
    match std::env::var(env) {
        Ok(val) => is_truthy(val.as_str()),
        Err(_) => false,
    }
}

/// Check if an environment variable is falsey
pub fn env_is_falsey(env: &str) -> bool {
    match std::env::var(env) {
        Ok(val) => is_falsey(val.as_str()),
        Err(_) => false,
    }
}

/// Check whether JSONL logging enabled
/// Set the `DYN_LOGGING_JSONL` environment variable a [`is_truthy`] value
pub fn jsonl_logging_enabled() -> bool {
    env_is_truthy("DYN_LOGGING_JSONL")
}

/// Check whether logging with ANSI terminal escape codes and colors is disabled.
/// Set the `DYN_SDK_DISABLE_ANSI_LOGGING` environment variable a [`is_truthy`] value
pub fn disable_ansi_logging() -> bool {
    env_is_truthy("DYN_SDK_DISABLE_ANSI_LOGGING")
}

/// Check whether to use local timezone for logging timestamps (default is UTC)
/// Set the `DYN_LOG_USE_LOCAL_TZ` environment variable to a [`is_truthy`] value
pub fn use_local_timezone() -> bool {
    env_is_truthy("DYN_LOG_USE_LOCAL_TZ")
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_runtime_config_with_env_vars() -> Result<()> {
        temp_env::with_vars(
            vec![
                ("DYN_RUNTIME_NUM_WORKER_THREADS", Some("24")),
                ("DYN_RUNTIME_MAX_BLOCKING_THREADS", Some("32")),
            ],
            || {
                let config = RuntimeConfig::from_settings()?;
                assert_eq!(config.num_worker_threads, Some(24));
                assert_eq!(config.max_blocking_threads, 32);
                Ok(())
            },
        )
    }

    #[test]
    fn test_runtime_config_defaults() -> Result<()> {
        temp_env::with_vars(
            vec![
                ("DYN_RUNTIME_NUM_WORKER_THREADS", None::<&str>),
                ("DYN_RUNTIME_MAX_BLOCKING_THREADS", Some("")),
            ],
            || {
                let config = RuntimeConfig::from_settings()?;

                let default_config = RuntimeConfig::default();
                assert_eq!(config.num_worker_threads, default_config.num_worker_threads);
                assert_eq!(
                    config.max_blocking_threads,
                    default_config.max_blocking_threads
                );
                Ok(())
            },
        )
    }

    #[test]
    fn test_runtime_config_rejects_invalid_thread_count() -> Result<()> {
        temp_env::with_vars(
            vec![
                ("DYN_RUNTIME_NUM_WORKER_THREADS", Some("0")),
                ("DYN_RUNTIME_MAX_BLOCKING_THREADS", Some("0")),
            ],
            || {
                let result = RuntimeConfig::from_settings();
                assert!(result.is_err());
                if let Err(e) = result {
                    assert!(e
                        .to_string()
                        .contains("num_worker_threads: Validation error"));
                    assert!(e
                        .to_string()
                        .contains("max_blocking_threads: Validation error"));
                }
                Ok(())
            },
        )
    }

    #[test]
    fn test_runtime_config_http_server_env_vars() -> Result<()> {
        temp_env::with_vars(
            vec![
                ("DYN_RUNTIME_HTTP_SERVER_HOST", Some("127.0.0.1")),
                ("DYN_RUNTIME_HTTP_SERVER_PORT", Some("9090")),
            ],
            || {
                let config = RuntimeConfig::from_settings()?;
                assert_eq!(config.http_server_host, "127.0.0.1");
                assert_eq!(config.http_server_port, 9090);
                Ok(())
            },
        )
    }

    #[test]
    fn test_http_server_enabled_by_default() {
        temp_env::with_vars(vec![("DYN_RUNTIME_HTTP_ENABLED", None::<&str>)], || {
            let config = RuntimeConfig::from_settings().unwrap();
            assert!(!config.http_server_enabled());
        });
    }

    #[test]
    fn test_http_server_disabled_explicitly() {
        temp_env::with_vars(vec![("DYN_RUNTIME_HTTP_ENABLED", Some("false"))], || {
            let config = RuntimeConfig::from_settings().unwrap();
            assert!(!config.http_server_enabled());
        });
    }

    #[test]
    fn test_http_server_enabled_explicitly() {
        temp_env::with_vars(vec![("DYN_RUNTIME_HTTP_ENABLED", Some("true"))], || {
            let config = RuntimeConfig::from_settings().unwrap();
            assert!(config.http_server_enabled());
        });
    }

    #[test]
    fn test_http_server_enabled_by_port() {
        temp_env::with_vars(vec![("DYN_RUNTIME_HTTP_SERVER_PORT", Some("8080"))], || {
            let config = RuntimeConfig::from_settings().unwrap();
            assert!(!config.http_server_enabled());
            assert_eq!(config.http_server_port, 8080);
        });
    }

    #[test]
    fn test_is_truthy_and_falsey() {
        // Test truthy values
        assert!(is_truthy("1"));
        assert!(is_truthy("true"));
        assert!(is_truthy("TRUE"));
        assert!(is_truthy("on"));
        assert!(is_truthy("yes"));

        // Test falsey values
        assert!(is_falsey("0"));
        assert!(is_falsey("false"));
        assert!(is_falsey("FALSE"));
        assert!(is_falsey("off"));
        assert!(is_falsey("no"));

        // Test opposite behavior
        assert!(!is_truthy("0"));
        assert!(!is_falsey("1"));

        // Test env functions
        temp_env::with_vars(vec![("TEST_TRUTHY", Some("true"))], || {
            assert!(env_is_truthy("TEST_TRUTHY"));
            assert!(!env_is_falsey("TEST_TRUTHY"));
        });

        temp_env::with_vars(vec![("TEST_FALSEY", Some("false"))], || {
            assert!(!env_is_truthy("TEST_FALSEY"));
            assert!(env_is_falsey("TEST_FALSEY"));
        });

        // Test missing env vars
        temp_env::with_vars(vec![("TEST_MISSING", None::<&str>)], || {
            assert!(!env_is_truthy("TEST_MISSING"));
            assert!(!env_is_falsey("TEST_MISSING"));
        });
    }
}
