codetether-agent 4.0.0

//! Crash reporting (opt-in)
//!
//! Captures panic metadata into local spool files and, when enabled, ships
//! pending reports to a remote ingestion endpoint on next startup.

use crate::config::Config;
use anyhow::{Context, Result};
use chrono::{DateTime, Utc};
use reqwest::StatusCode;
use serde::{Deserialize, Serialize};
use std::backtrace::Backtrace;
use std::io::{self, Write};
use std::panic;
use std::path::{Path, PathBuf};
use std::sync::Once;
use std::time::Duration;
use uuid::Uuid;

const REPORT_VERSION: u32 = 1;
const CRASH_SCHEMA: &str = "codetether.crash.v1";
const CRASH_SOURCE: &str = "codetether-agent";
const MAX_PENDING_REPORTS: usize = 50;
const MAX_PANIC_MESSAGE_CHARS: usize = 2048;
const MAX_BACKTRACE_CHARS: usize = 32_000;
const MAX_COMMAND_CHARS: usize = 1024;

const CRASH_UPLOAD_STATE_FILE: &str = "crash-upload-state.json";
const MIN_UPLOAD_BACKOFF_SECS: u64 = 5 * 60; // 5 minutes
const MAX_UPLOAD_BACKOFF_SECS: u64 = 24 * 60 * 60; // 24 hours
const MAX_STATUS_FAILURES_PER_FLUSH: usize = 3;

const ENV_CRASH_REPORT_AUTH_TOKEN: &str = "CODETETHER_CRASH_REPORT_AUTH_TOKEN";
const ENV_CRASH_REPORT_API_KEY: &str = "CODETETHER_CRASH_REPORT_API_KEY";

#[derive(Debug, Clone)]
struct CrashReporterSettings {
    enabled: bool,
    endpoint: String,
    report_dir: PathBuf,
    app_version: String,
    command_line: String,
    install_id: String,
    auth_token: Option<String>,
    api_key: Option<String>,
}

impl CrashReporterSettings {
    fn from_config(config: &Config) -> Self {
        let install_id = match load_or_create_install_id() {
            Ok(id) => id,
            Err(err) => {
                tracing::warn!(error = %err, "Failed to load persistent install ID; using ephemeral value");
                Uuid::new_v4().to_string()
            }
        };

        Self {
            enabled: config.telemetry.crash_reporting_enabled(),
            endpoint: config.telemetry.crash_report_endpoint(),
            report_dir: crash_report_dir(),
            app_version: env!("CARGO_PKG_VERSION").to_string(),
            command_line: truncate_with_ellipsis(
                &std::env::args().collect::<Vec<_>>().join(" "),
                MAX_COMMAND_CHARS,
            ),
            install_id,
            auth_token: env_non_empty(ENV_CRASH_REPORT_AUTH_TOKEN),
            api_key: env_non_empty(ENV_CRASH_REPORT_API_KEY),
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct CrashReport {
    report_version: u32,
    report_id: String,
    occurred_at: DateTime<Utc>,
    app_version: String,
    command_line: String,
    os: String,
    arch: String,
    process_id: u32,
    thread_name: String,
    panic_message: String,
    panic_location: Option<String>,
    backtrace: String,
}

impl CrashReport {
    fn from_panic_info(
        settings: &CrashReporterSettings,
        panic_info: &panic::PanicHookInfo<'_>,
    ) -> Self {
        let panic_message = panic_payload_to_string(panic_info);
        let panic_location = panic_info
            .location()
            .map(|loc| format!("{}:{}:{}", loc.file(), loc.line(), loc.column()));
        let thread_name = std::thread::current()
            .name()
            .map(|s| s.to_string())
            .unwrap_or_else(|| "unnamed".to_string());
        let backtrace = Backtrace::force_capture().to_string();

        Self {
            report_version: REPORT_VERSION,
            report_id: Uuid::new_v4().to_string(),
            occurred_at: Utc::now(),
            app_version: settings.app_version.clone(),
            command_line: settings.command_line.clone(),
            os: std::env::consts::OS.to_string(),
            arch: std::env::consts::ARCH.to_string(),
            process_id: std::process::id(),
            thread_name,
            panic_message: truncate_with_ellipsis(&panic_message, MAX_PANIC_MESSAGE_CHARS),
            panic_location,
            backtrace: truncate_with_ellipsis(&backtrace, MAX_BACKTRACE_CHARS),
        }
    }
}

#[derive(Debug, Clone, Serialize)]
struct CrashEnvelope<'a> {
    schema: &'static str,
    source: &'static str,
    sent_at: DateTime<Utc>,
    install_id: &'a str,
    report: &'a CrashReport,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
struct CrashUploadState {
    /// Number of consecutive flush attempts that failed without sending any reports.
    consecutive_failures: u32,
    /// Do not attempt upload again until this time (UTC).
    next_attempt_at: Option<DateTime<Utc>>,
    /// Last attempt timestamp.
    last_attempt_at: Option<DateTime<Utc>>,
    /// Last error (truncated) for diagnostics.
    last_error: Option<String>,
}

pub async fn maybe_prompt_for_consent(config: &Config, allow_prompt: bool) -> Config {
    if !allow_prompt {
        return config.clone();
    }

    if config.telemetry.crash_reporting.is_some() || config.telemetry.crash_reporting_prompted() {
        return config.clone();
    }

    println!();
    println!("CodeTether Optional Crash Reporting");
    println!("- Helps us fix catastrophic crashes faster.");
    println!("- Sends panic message, stack trace, app version, OS/arch, and command.");
    println!("- Does not intentionally include API keys or source files.");
    println!(
        "- You can change this any time with `codetether config --set telemetry.crash_reporting=true|false`."
    );

    let enabled = match prompt_yes_no("Enable crash reporting now? [y/N]: ") {
        Ok(v) => v,
        Err(err) => {
            tracing::warn!(error = %err, "Failed to collect crash reporting consent input");
            return config.clone();
        }
    };

    if let Err(err) = persist_consent_choice(enabled).await {
        tracing::warn!(error = %err, "Failed to persist crash reporting consent choice");
        return config.clone();
    }

    if enabled {
        println!("Crash reporting enabled.");
        if env_non_empty(ENV_CRASH_REPORT_AUTH_TOKEN).is_none()
            && env_non_empty(ENV_CRASH_REPORT_API_KEY).is_none()
        {
            println!(
                "If your telemetry endpoint requires auth, set {} or {}.",
                ENV_CRASH_REPORT_AUTH_TOKEN, ENV_CRASH_REPORT_API_KEY
            );
        }
    } else {
        println!("Crash reporting disabled.");
    }

    match Config::load().await {
        Ok(updated) => updated,
        Err(err) => {
            tracing::warn!(error = %err, "Failed to reload config after consent update");
            config.clone()
        }
    }
}

pub async fn initialize(config: &Config) {
    let settings = CrashReporterSettings::from_config(config);
    install_panic_hook(settings.clone());

    if !settings.enabled {
        return;
    }

    if settings.auth_token.is_none() && settings.api_key.is_none() {
        tracing::info!(
            "Crash reporting enabled without auth headers. Set CODETETHER_CRASH_REPORT_AUTH_TOKEN or CODETETHER_CRASH_REPORT_API_KEY if your endpoint requires authentication."
        );
    }

    if let Err(err) = flush_pending_reports(&settings).await {
        tracing::warn!(error = %err, "Failed to flush pending crash reports");
    }
}

fn install_panic_hook(settings: CrashReporterSettings) {
    static PANIC_HOOK_ONCE: Once = Once::new();
    PANIC_HOOK_ONCE.call_once(|| {
        let default_hook = panic::take_hook();
        panic::set_hook(Box::new(move |panic_info| {
            let persisted = persist_crash_report(&settings, panic_info);
            default_hook(panic_info);

            match persisted {
                Ok(path) if settings.enabled => {
                    eprintln!(
                        "codetether: crash report queued at '{}' and will be sent on next startup.",
                        path.display()
                    );
                }
                Ok(path) => {
                    eprintln!(
                        "codetether: crash report saved at '{}'. Crash reporting is disabled (opt-in).",
                        path.display()
                    );
                    eprintln!(
                        "codetether: enable with `codetether config --set telemetry.crash_reporting=true`"
                    );
                }
                Err(err) => {
                    eprintln!("codetether: failed to persist crash report: {err}");
                }
            }
        }));
    });
}

fn persist_crash_report(
    settings: &CrashReporterSettings,
    panic_info: &panic::PanicHookInfo<'_>,
) -> Result<PathBuf> {
    std::fs::create_dir_all(&settings.report_dir)
        .with_context(|| format!("create report dir {}", settings.report_dir.display()))?;

    let report = CrashReport::from_panic_info(settings, panic_info);
    let file_name = format!(
        "{}-{}.json",
        report.occurred_at.format("%Y%m%dT%H%M%S%.3fZ"),
        report.report_id
    );
    let path = settings.report_dir.join(file_name);
    let payload = serde_json::to_string_pretty(&report)?;
    std::fs::write(&path, payload).with_context(|| format!("write report {}", path.display()))?;

    prune_old_reports(&settings.report_dir, MAX_PENDING_REPORTS)?;
    Ok(path)
}

fn prune_old_reports(report_dir: &Path, max_reports: usize) -> Result<()> {
    let mut reports = pending_report_paths(report_dir)?;
    if reports.len() <= max_reports {
        return Ok(());
    }

    reports.sort_by_key(|path| {
        std::fs::metadata(path)
            .ok()
            .and_then(|meta| meta.modified().ok())
    });

    let remove_count = reports.len().saturating_sub(max_reports);
    for path in reports.into_iter().take(remove_count) {
        if let Err(err) = std::fs::remove_file(&path) {
            tracing::warn!(path = %path.display(), error = %err, "Failed pruning old crash report");
        }
    }

    Ok(())
}

fn pending_report_paths(report_dir: &Path) -> Result<Vec<PathBuf>> {
    if !report_dir.exists() {
        return Ok(Vec::new());
    }

    let mut paths = Vec::new();
    for entry in std::fs::read_dir(report_dir)? {
        let entry = entry?;
        let path = entry.path();
        if path.extension().is_some_and(|ext| ext == "json") {
            paths.push(path);
        }
    }

    paths.sort_by_key(|path| {
        std::fs::metadata(path)
            .ok()
            .and_then(|meta| meta.modified().ok())
    });

    Ok(paths)
}

async fn flush_pending_reports(settings: &CrashReporterSettings) -> Result<()> {
    // Persistent backoff: if the endpoint is down / network is unavailable, don't
    // spam the logs by retrying every queued crash report on every startup.
    if should_skip_upload_due_to_backoff(settings).await {
        return Ok(());
    }

    let paths = pending_report_paths(&settings.report_dir)?;
    if paths.is_empty() {
        return Ok(());
    }

    let client = reqwest::Client::builder()
        .timeout(Duration::from_secs(8))
        .user_agent(format!("codetether/{}", settings.app_version))
        .build()
        .context("build crash reporting HTTP client")?;

    let mut sent = 0usize;
    let mut failed = 0usize;
    let mut status_failures = 0usize;
    let mut transport_error: Option<anyhow::Error> = None;

    for path in paths {
        let raw = match tokio::fs::read_to_string(&path).await {
            Ok(content) => content,
            Err(err) => {
                failed += 1;
                tracing::warn!(path = %path.display(), error = %err, "Failed reading crash report");
                continue;
            }
        };

        let report: CrashReport = match serde_json::from_str(&raw) {
            Ok(report) => report,
            Err(err) => {
                failed += 1;
                tracing::warn!(
                    path = %path.display(),
                    error = %err,
                    "Invalid crash report format; dropping file"
                );
                let _ = tokio::fs::remove_file(&path).await;
                continue;
            }
        };

        match upload_report(settings, &client, &report).await {
            Ok(true) => {
                sent += 1;
                if let Err(err) = tokio::fs::remove_file(&path).await {
                    tracing::warn!(
                        path = %path.display(),
                        error = %err,
                        "Failed deleting uploaded crash report"
                    );
                }
            }
            Ok(false) => {
                failed += 1;
                status_failures += 1;
                if status_failures >= MAX_STATUS_FAILURES_PER_FLUSH {
                    tracing::warn!(
                        failures = status_failures,
                        endpoint = %settings.endpoint,
                        "Crash report uploads are being rejected; stopping this flush to avoid log spam"
                    );
                    break;
                }
            }
            Err(err) => {
                failed += 1;
                // Transport errors (DNS/TLS/timeout) will repeat for every queued report.
                // Log once and stop trying until the next backoff window.
                transport_error = Some(err);
                break;
            }
        }
    }

    // Update persistent backoff state.
    // - If we sent at least one report, reset failures.
    // - If we sent none and had transport failure or repeated rejections, increase backoff.
    if sent > 0 {
        let _ = save_upload_state(
            CrashUploadState {
                consecutive_failures: 0,
                next_attempt_at: None,
                last_attempt_at: Some(Utc::now()),
                last_error: None,
            },
            settings,
        )
        .await;
    } else if failed > 0 {
        let err_str = transport_error
            .as_ref()
            .map(|e| truncate_with_ellipsis(&format!("{e}"), 300));

        let _ = bump_upload_backoff(err_str, settings).await;

        if let Some(err) = transport_error {
            tracing::warn!(
                endpoint = %settings.endpoint,
                error = %err,
                "Crash report upload failed (transport). Backing off and will retry later."
            );
        }
    }

    tracing::info!(
        sent = sent,
        failed = failed,
        endpoint = %settings.endpoint,
        "Crash report sync complete"
    );

    Ok(())
}

async fn should_skip_upload_due_to_backoff(settings: &CrashReporterSettings) -> bool {
    let Some(state) = load_upload_state(settings).await else {
        return false;
    };

    let Some(next) = state.next_attempt_at else {
        return false;
    };

    let now = Utc::now();
    if next > now {
        let secs = (next - now).num_seconds().max(0);
        tracing::info!(
            endpoint = %settings.endpoint,
            retry_in_secs = secs,
            consecutive_failures = state.consecutive_failures,
            "Skipping crash report upload due to backoff"
        );
        return true;
    }

    false
}

async fn load_upload_state(settings: &CrashReporterSettings) -> Option<CrashUploadState> {
    let path = crash_upload_state_path(settings);
    let raw = tokio::fs::read_to_string(&path).await.ok()?;
    serde_json::from_str(&raw).ok()
}

async fn save_upload_state(
    state: CrashUploadState,
    settings: &CrashReporterSettings,
) -> Result<()> {
    let path = crash_upload_state_path(settings);
    if let Some(parent) = path.parent() {
        tokio::fs::create_dir_all(parent)
            .await
            .with_context(|| format!("create crash telemetry dir {}", parent.display()))?;
    }
    let raw = serde_json::to_string_pretty(&state).context("serialize crash upload state")?;
    tokio::fs::write(&path, raw)
        .await
        .with_context(|| format!("write crash upload state {}", path.display()))?;
    Ok(())
}

async fn bump_upload_backoff(
    last_error: Option<String>,
    settings: &CrashReporterSettings,
) -> Result<()> {
    let mut state = load_upload_state(settings).await.unwrap_or_default();
    state.consecutive_failures = state.consecutive_failures.saturating_add(1);
    state.last_attempt_at = Some(Utc::now());
    state.last_error = last_error;

    let backoff = compute_backoff_secs(state.consecutive_failures);
    state.next_attempt_at = Some(Utc::now() + chrono::Duration::seconds(backoff as i64));

    save_upload_state(state, settings).await
}

fn compute_backoff_secs(consecutive_failures: u32) -> u64 {
    // Exponential backoff: 5m, 10m, 20m, ... capped at 24h
    // Clamp exponent so we don't overflow.
    let exp = consecutive_failures.saturating_sub(1).min(10);
    let factor = 1u64.checked_shl(exp).unwrap_or(u64::MAX);
    let backoff = MIN_UPLOAD_BACKOFF_SECS.saturating_mul(factor);
    backoff.clamp(MIN_UPLOAD_BACKOFF_SECS, MAX_UPLOAD_BACKOFF_SECS)
}

fn crash_upload_state_path(settings: &CrashReporterSettings) -> PathBuf {
    // Keep it next to install_id under telemetry/ so it's easy to find.
    // Use settings.report_dir's sibling to avoid depending on OS-specific paths.
    // report_dir = <data>/crash-reports
    // state_dir  = <data>/telemetry
    let data_dir = settings
        .report_dir
        .parent()
        .map(Path::to_path_buf)
        .unwrap_or_else(|| codetether_data_dir());
    data_dir.join("telemetry").join(CRASH_UPLOAD_STATE_FILE)
}

async fn upload_report(
    settings: &CrashReporterSettings,
    client: &reqwest::Client,
    report: &CrashReport,
) -> Result<bool> {
    let envelope = CrashEnvelope {
        schema: CRASH_SCHEMA,
        source: CRASH_SOURCE,
        sent_at: Utc::now(),
        install_id: &settings.install_id,
        report,
    };

    let response = build_upload_request(settings, client, report)
        .json(&envelope)
        .send()
        .await
        .context("send schema crash payload")?;

    let status = response.status();
    if status.is_success() {
        return Ok(true);
    }

    if should_retry_with_legacy_payload(status) {
        tracing::info!(
            status = %status,
            report_id = %report.report_id,
            "Crash endpoint rejected schema envelope; trying legacy payload"
        );

        let legacy_response = build_upload_request(settings, client, report)
            .header("X-CodeTether-Payload", "legacy")
            .json(report)
            .send()
            .await
            .context("send legacy crash payload")?;

        if legacy_response.status().is_success() {
            return Ok(true);
        }

        tracing::warn!(
            status = %legacy_response.status(),
            report_id = %report.report_id,
            "Crash report upload failed for both schema and legacy payloads"
        );
        return Ok(false);
    }

    tracing::warn!(
        status = %status,
        report_id = %report.report_id,
        "Crash report upload rejected"
    );
    Ok(false)
}

fn build_upload_request(
    settings: &CrashReporterSettings,
    client: &reqwest::Client,
    report: &CrashReport,
) -> reqwest::RequestBuilder {
    let mut request = client
        .post(&settings.endpoint)
        .header("X-CodeTether-Schema", CRASH_SCHEMA)
        .header("X-CodeTether-Source", CRASH_SOURCE)
        .header("X-CodeTether-Install-Id", &settings.install_id)
        .header("X-CodeTether-Report-Id", &report.report_id)
        .header("X-CodeTether-App-Version", &settings.app_version);

    if let Some(token) = &settings.auth_token {
        request = request.bearer_auth(token);
    }
    if let Some(api_key) = &settings.api_key {
        request = request.header("X-CodeTether-API-Key", api_key);
    }

    request
}

fn should_retry_with_legacy_payload(status: StatusCode) -> bool {
    matches!(
        status,
        StatusCode::BAD_REQUEST
            | StatusCode::NOT_FOUND
            | StatusCode::UNSUPPORTED_MEDIA_TYPE
            | StatusCode::UNPROCESSABLE_ENTITY
    )
}

fn crash_report_dir() -> PathBuf {
    codetether_data_dir().join("crash-reports")
}

fn install_id_path() -> PathBuf {
    codetether_data_dir().join("telemetry").join("install_id")
}

fn codetether_data_dir() -> PathBuf {
    Config::data_dir().unwrap_or_else(|| PathBuf::from("/tmp/codetether-agent"))
}

fn load_or_create_install_id() -> Result<String> {
    let path = install_id_path();
    if let Ok(existing) = std::fs::read_to_string(&path) {
        let trimmed = existing.trim();
        if !trimmed.is_empty() {
            return Ok(trimmed.to_string());
        }
    }

    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)
            .with_context(|| format!("create telemetry directory {}", parent.display()))?;
    }

    let new_id = Uuid::new_v4().to_string();
    std::fs::write(&path, format!("{new_id}\n"))
        .with_context(|| format!("write install id {}", path.display()))?;
    Ok(new_id)
}

fn env_non_empty(key: &str) -> Option<String> {
    std::env::var(key)
        .ok()
        .map(|value| value.trim().to_string())
        .filter(|value| !value.is_empty())
}

async fn persist_consent_choice(enabled: bool) -> Result<()> {
    let enabled_value = if enabled { "true" } else { "false" };
    Config::set("telemetry.crash_reporting", enabled_value).await?;
    Config::set("telemetry.crash_reporting_prompted", "true").await?;
    Ok(())
}

fn prompt_yes_no(prompt: &str) -> io::Result<bool> {
    let mut stdout = io::stdout();

    loop {
        write!(stdout, "{prompt}")?;
        stdout.flush()?;

        let mut input = String::new();
        io::stdin().read_line(&mut input)?;

        let normalized = input.trim().to_ascii_lowercase();
        if normalized.is_empty() {
            return Ok(false);
        }
        if matches!(normalized.as_str(), "y" | "yes") {
            return Ok(true);
        }
        if matches!(normalized.as_str(), "n" | "no") {
            return Ok(false);
        }

        writeln!(stdout, "Please answer 'y' or 'n'.")?;
    }
}

fn panic_payload_to_string(panic_info: &panic::PanicHookInfo<'_>) -> String {
    if let Some(msg) = panic_info.payload().downcast_ref::<&str>() {
        (*msg).to_string()
    } else if let Some(msg) = panic_info.payload().downcast_ref::<String>() {
        msg.clone()
    } else {
        "non-string panic payload".to_string()
    }
}

fn truncate_with_ellipsis(value: &str, max_chars: usize) -> String {
    if max_chars == 0 {
        return String::new();
    }

    let mut chars = value.chars();
    let mut output = String::new();
    for _ in 0..max_chars {
        if let Some(ch) = chars.next() {
            output.push(ch);
        } else {
            return value.to_string();
        }
    }

    if chars.next().is_some() {
        format!("{output}...")
    } else {
        output
    }
}

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

    #[test]
    fn backoff_increases_and_clamps() {
        // First failure uses the minimum.
        assert_eq!(compute_backoff_secs(1), MIN_UPLOAD_BACKOFF_SECS);
        // Second failure doubles.
        assert_eq!(compute_backoff_secs(2), MIN_UPLOAD_BACKOFF_SECS * 2);
        // A larger number should never exceed the max cap.
        assert_eq!(compute_backoff_secs(10_000), MAX_UPLOAD_BACKOFF_SECS);
    }
}