//! Default Codex HTTP client: shared `User-Agent`, `originator`, optional residency header, and
//! reqwest/`CodexHttpClient` construction.
//!
//! Use [`crate::default_client`] or [`codex_login::default_client`] from other crates in this
//! workspace.

use codex_client::BuildCustomCaTransportError;
use codex_client::CodexHttpClient;
pub use codex_client::CodexRequestBuilder;
use codex_client::build_reqwest_client_with_custom_ca;
use codex_client::with_chatgpt_cloudflare_cookie_store;
use codex_terminal_detection::user_agent;
use reqwest::header::HeaderMap;
use reqwest::header::HeaderValue;
use reqwest::header::USER_AGENT;
use std::sync::LazyLock;
use std::sync::Mutex;
use std::sync::RwLock;

/// Set this to add a suffix to the User-Agent string.
///
/// It is not ideal that we're using a global singleton for this.
/// This is primarily designed to differentiate MCP clients from each other.
/// Because there can only be one MCP server per process, it should be safe for this to be a global static.
/// However, future users of this should use this with caution as a result.
/// In addition, we want to be confident that this value is used for ALL clients and doing that requires a
/// lot of wiring and it's easy to miss code paths by doing so.
/// See https://github.com/openai/codex/pull/3388/files for an example of what that would look like.
/// Finally, we want to make sure this is set for ALL mcp clients without needing to know a special env var
/// or having to set data that they already specified in the mcp initialize request somewhere else.
///
/// A space is automatically added between the suffix and the rest of the User-Agent string.
/// The full user agent string is returned from the mcp initialize response.
/// Parenthesis will be added by Codex. This should only specify what goes inside of the parenthesis.
pub static USER_AGENT_SUFFIX: LazyLock<Mutex<Option<String>>> = LazyLock::new(|| Mutex::new(None));
pub const DEFAULT_ORIGINATOR: &str = "codex_cli_rs";
pub const CODEX_INTERNAL_ORIGINATOR_OVERRIDE_ENV_VAR: &str = "CODEX_INTERNAL_ORIGINATOR_OVERRIDE";
pub const RESIDENCY_HEADER_NAME: &str = "x-openai-internal-codex-residency";

pub use codex_config::ResidencyRequirement;

#[derive(Debug, Clone)]
pub struct Originator {
    pub value: String,
    pub header_value: HeaderValue,
}
static ORIGINATOR: LazyLock<RwLock<Option<Originator>>> = LazyLock::new(|| RwLock::new(None));
static REQUIREMENTS_RESIDENCY: LazyLock<RwLock<Option<ResidencyRequirement>>> =
    LazyLock::new(|| RwLock::new(None));

#[derive(Debug)]
pub enum SetOriginatorError {
    InvalidHeaderValue,
    AlreadyInitialized,
}

fn get_originator_value(provided: Option<String>) -> Originator {
    let value = std::env::var(CODEX_INTERNAL_ORIGINATOR_OVERRIDE_ENV_VAR)
        .ok()
        .or(provided)
        .unwrap_or(DEFAULT_ORIGINATOR.to_string());

    match HeaderValue::from_str(&value) {
        Ok(header_value) => Originator {
            value,
            header_value,
        },
        Err(e) => {
            tracing::error!("Unable to turn originator override {value} into header value: {e}");
            Originator {
                value: DEFAULT_ORIGINATOR.to_string(),
                header_value: HeaderValue::from_static(DEFAULT_ORIGINATOR),
            }
        }
    }
}

pub fn set_default_originator(value: String) -> Result<(), SetOriginatorError> {
    if HeaderValue::from_str(&value).is_err() {
        return Err(SetOriginatorError::InvalidHeaderValue);
    }
    let originator = get_originator_value(Some(value));
    let Ok(mut guard) = ORIGINATOR.write() else {
        return Err(SetOriginatorError::AlreadyInitialized);
    };
    if guard.is_some() {
        return Err(SetOriginatorError::AlreadyInitialized);
    }
    *guard = Some(originator);
    Ok(())
}

pub fn set_default_client_residency_requirement(enforce_residency: Option<ResidencyRequirement>) {
    let Ok(mut guard) = REQUIREMENTS_RESIDENCY.write() else {
        tracing::warn!("Failed to acquire requirements residency lock");
        return;
    };
    *guard = enforce_residency;
}

pub fn originator() -> Originator {
    if let Ok(guard) = ORIGINATOR.read()
        && let Some(originator) = guard.as_ref()
    {
        return originator.clone();
    }

    if std::env::var(CODEX_INTERNAL_ORIGINATOR_OVERRIDE_ENV_VAR).is_ok() {
        let originator = get_originator_value(/*provided*/ None);
        if let Ok(mut guard) = ORIGINATOR.write() {
            match guard.as_ref() {
                Some(originator) => return originator.clone(),
                None => *guard = Some(originator.clone()),
            }
        }
        return originator;
    }

    get_originator_value(/*provided*/ None)
}

pub fn is_first_party_originator(originator_value: &str) -> bool {
    originator_value == DEFAULT_ORIGINATOR
        || originator_value == "codex-tui"
        || originator_value == "codex_vscode"
        || originator_value.starts_with("Codex ")
}

pub fn is_first_party_chat_originator(originator_value: &str) -> bool {
    originator_value == "codex_atlas" || originator_value == "codex_chatgpt_desktop"
}

pub fn get_codex_user_agent() -> String {
    let build_version = env!("CARGO_PKG_VERSION");
    let os_info = os_info::get();
    let originator = originator();
    let prefix = format!(
        "{}/{build_version} ({} {}; {}) {}",
        originator.value.as_str(),
        os_info.os_type(),
        os_info.version(),
        os_info.architecture().unwrap_or("unknown"),
        user_agent()
    );
    let suffix = USER_AGENT_SUFFIX
        .lock()
        .ok()
        .and_then(|guard| guard.clone());
    let suffix = suffix
        .as_deref()
        .map(str::trim)
        .filter(|value| !value.is_empty())
        .map_or_else(String::new, |value| format!(" ({value})"));

    let candidate = format!("{prefix}{suffix}");
    sanitize_user_agent(candidate, &prefix)
}

/// Sanitize the user agent string.
///
/// Invalid characters are replaced with an underscore.
///
/// If the user agent fails to parse, it falls back to fallback and then to ORIGINATOR.
fn sanitize_user_agent(candidate: String, fallback: &str) -> String {
    if HeaderValue::from_str(candidate.as_str()).is_ok() {
        return candidate;
    }

    let sanitized: String = candidate
        .chars()
        .map(|ch| if matches!(ch, ' '..='~') { ch } else { '_' })
        .collect();
    if !sanitized.is_empty() && HeaderValue::from_str(sanitized.as_str()).is_ok() {
        tracing::warn!(
            "Sanitized Codex user agent because provided suffix contained invalid header characters"
        );
        sanitized
    } else if HeaderValue::from_str(fallback).is_ok() {
        tracing::warn!(
            "Falling back to base Codex user agent because provided suffix could not be sanitized"
        );
        fallback.to_string()
    } else {
        tracing::warn!(
            "Falling back to default Codex originator because base user agent string is invalid"
        );
        originator().value
    }
}

/// Create an HTTP client with default `originator` and `User-Agent` headers set.
pub fn create_client() -> CodexHttpClient {
    let inner = build_reqwest_client();
    CodexHttpClient::new(inner)
}

/// Builds the default reqwest client used for ordinary Codex HTTP traffic.
///
/// This starts from the standard Codex user agent, default headers, and sandbox-specific proxy
/// policy, then layers in shared custom CA handling from `CODEX_CA_CERTIFICATE` /
/// `SSL_CERT_FILE`. The function remains infallible for compatibility with existing call sites, so
/// a custom-CA or builder failure is logged and falls back to `reqwest::Client::new()`.
pub fn build_reqwest_client() -> reqwest::Client {
    try_build_reqwest_client().unwrap_or_else(|error| {
        tracing::warn!(error = %error, "failed to build default reqwest client");
        with_chatgpt_cloudflare_cookie_store(reqwest::Client::builder())
            .build()
            .unwrap_or_else(|fallback_error| {
                tracing::warn!(
                    error = %fallback_error,
                    "failed to build fallback reqwest client with ChatGPT Cloudflare cookie store"
                );
                reqwest::Client::new()
            })
    })
}

/// Tries to build the default reqwest client used for ordinary Codex HTTP traffic.
///
/// Callers that need a structured CA-loading failure instead of the legacy logged fallback can use
/// this method directly.
pub fn try_build_reqwest_client() -> Result<reqwest::Client, BuildCustomCaTransportError> {
    let mut builder = reqwest::Client::builder().default_headers(default_headers());
    if is_sandboxed() {
        builder = builder.no_proxy();
    }
    builder = with_chatgpt_cloudflare_cookie_store(builder);

    build_reqwest_client_with_custom_ca(builder)
}

pub fn default_headers() -> HeaderMap {
    let mut headers = HeaderMap::new();
    headers.insert("originator", originator().header_value);
    if let Ok(user_agent) = HeaderValue::from_str(&get_codex_user_agent()) {
        headers.insert(USER_AGENT, user_agent);
    }
    if let Ok(guard) = REQUIREMENTS_RESIDENCY.read()
        && let Some(requirement) = guard.as_ref()
        && !headers.contains_key(RESIDENCY_HEADER_NAME)
    {
        let value = match requirement {
            ResidencyRequirement::Us => HeaderValue::from_static("us"),
        };
        headers.insert(RESIDENCY_HEADER_NAME, value);
    }
    headers
}

fn is_sandboxed() -> bool {
    std::env::var("CODEX_SANDBOX").as_deref() == Ok("seatbelt")
}

#[cfg(test)]
#[path = "default_client_tests.rs"]
mod tests;
