use axum::http::StatusCode;
use module_runtime::RuntimeTrackingScopeKind;
use platform_image::PlatformImageFailureAudit;
use serde_json::{Value, json};
use time::OffsetDateTime;
use uuid::Uuid;

use crate::{state::AppState, tracking::TrackingEventDraft};

pub(crate) const EXTERNAL_API_FAILURE_EVENT_KEY: &str = "external_api_call_failure";
pub(crate) const EXTERNAL_API_AUDIT_MODULE_KEY: &str = "external-api";

#[derive(Clone, Debug)]
pub(crate) struct ExternalApiFailureDraft {
    pub(crate) provider: &'static str,
    pub(crate) endpoint: String,
    pub(crate) operation: String,
    pub(crate) failure_stage: &'static str,
    pub(crate) status_code: Option<u16>,
    pub(crate) status_class: Option<&'static str>,
    pub(crate) timeout: bool,
    pub(crate) retryable: bool,
    pub(crate) error_message: String,
    pub(crate) error_source: Option<String>,
    pub(crate) raw_excerpt: Option<String>,
    pub(crate) latency_ms: Option<u64>,
    pub(crate) prompt_chars: Option<usize>,
    pub(crate) reference_image_count: Option<usize>,
    pub(crate) image_model: Option<&'static str>,
}

impl ExternalApiFailureDraft {
    pub(crate) fn new(
        provider: &'static str,
        endpoint: impl Into<String>,
        operation: impl Into<String>,
        failure_stage: &'static str,
        error_message: impl Into<String>,
    ) -> Self {
        Self {
            provider,
            endpoint: endpoint.into(),
            operation: operation.into(),
            failure_stage,
            status_code: None,
            status_class: None,
            timeout: false,
            retryable: false,
            error_message: error_message.into(),
            error_source: None,
            raw_excerpt: None,
            latency_ms: None,
            prompt_chars: None,
            reference_image_count: None,
            image_model: None,
        }
    }

    pub(crate) fn with_status_code(mut self, status_code: Option<u16>) -> Self {
        self.status_code = status_code;
        self
    }

    pub(crate) fn with_optional_status_class(mut self, status_class: Option<&'static str>) -> Self {
        self.status_class = status_class;
        self
    }

    pub(crate) fn with_timeout(mut self, timeout: bool) -> Self {
        self.timeout = timeout;
        self
    }

    pub(crate) fn with_retryable(mut self, retryable: bool) -> Self {
        self.retryable = retryable;
        self
    }

    pub(crate) fn with_error_source(mut self, error_source: Option<String>) -> Self {
        self.error_source = error_source;
        self
    }

    pub(crate) fn with_raw_excerpt(mut self, raw_excerpt: Option<String>) -> Self {
        self.raw_excerpt = raw_excerpt;
        self
    }

    pub(crate) fn with_latency_ms(mut self, latency_ms: Option<u64>) -> Self {
        self.latency_ms = latency_ms;
        self
    }

    pub(crate) fn with_prompt_chars(mut self, prompt_chars: Option<usize>) -> Self {
        self.prompt_chars = prompt_chars;
        self
    }

    pub(crate) fn with_reference_image_count(
        mut self,
        reference_image_count: Option<usize>,
    ) -> Self {
        self.reference_image_count = reference_image_count;
        self
    }

    pub(crate) fn with_image_model(mut self, image_model: Option<&'static str>) -> Self {
        self.image_model = image_model;
        self
    }
}

pub(crate) fn build_external_api_failure_draft_from_platform_image_audit(
    audit: &PlatformImageFailureAudit,
) -> ExternalApiFailureDraft {
    ExternalApiFailureDraft::new(
        audit.provider,
        audit.endpoint.clone(),
        audit.operation.clone(),
        audit.failure_stage,
        audit.error_message.clone(),
    )
    .with_status_code(audit.status_code)
    .with_optional_status_class(audit.status_class)
    .with_timeout(audit.timeout)
    .with_retryable(audit.retryable)
    .with_error_source(audit.error_source.clone())
    .with_raw_excerpt(audit.raw_excerpt.clone())
    .with_latency_ms(audit.latency_ms)
    .with_prompt_chars(audit.prompt_chars)
    .with_reference_image_count(audit.reference_image_count)
    .with_image_model(audit.image_model)
}

/// 中文注释：下载图片、OSS 读写等非标准 HTTP 状态统一显式归类，避免 OTLP 低基数 label 误落到 `transport`。
pub(crate) fn app_error_status_class(status_code: StatusCode) -> &'static str {
    status_class(Some(status_code.as_u16()))
}

/// 中文注释：外部供应商失败同时进入 OTLP 和 tracking_event；失败审计不能反向阻断主业务错误返回。
pub(crate) async fn record_external_api_failure(state: &AppState, draft: ExternalApiFailureDraft) {
    record_external_api_failure_otlp(&draft);

    let tracking_event = build_external_api_failure_tracking_draft(&draft);
    if let Some(outbox) = state.tracking_outbox() {
        match outbox
            .enqueue(crate::tracking::build_tracking_event_input(
                tracking_event.clone(),
            ))
            .await
        {
            Ok(crate::tracking_outbox::TrackingOutboxEnqueueOutcome::Enqueued) => {}
            Ok(crate::tracking_outbox::TrackingOutboxEnqueueOutcome::Dropped { reason }) => {
                tracing::warn!(
                    provider = draft.provider,
                    endpoint = %draft.endpoint,
                    operation = %draft.operation,
                    failure_stage = draft.failure_stage,
                    reason,
                    "外部 API 失败审计写入 outbox 被保护阈值拒绝，回退同步直写 SpacetimeDB"
                );
                crate::tracking::record_tracking_event_after_success(
                    state,
                    &audit_request_context(),
                    tracking_event,
                )
                .await;
            }
            Err(error) => {
                tracing::warn!(
                    provider = draft.provider,
                    endpoint = %draft.endpoint,
                    operation = %draft.operation,
                    failure_stage = draft.failure_stage,
                    error = %error,
                    "外部 API 失败审计写入 outbox 失败，回退同步直写 SpacetimeDB"
                );
                crate::tracking::record_tracking_event_after_success(
                    state,
                    &audit_request_context(),
                    tracking_event,
                )
                .await;
            }
        }
        return;
    }

    crate::tracking::record_tracking_event_after_success(
        state,
        &audit_request_context(),
        tracking_event,
    )
    .await;
}

pub(crate) fn build_external_api_failure_tracking_draft(
    failure: &ExternalApiFailureDraft,
) -> TrackingEventDraft {
    let mut draft = TrackingEventDraft::new(
        EXTERNAL_API_FAILURE_EVENT_KEY,
        EXTERNAL_API_AUDIT_MODULE_KEY,
    );
    draft.scope_kind = RuntimeTrackingScopeKind::Module;
    draft.scope_id = failure.provider.to_string();
    draft.metadata = build_external_api_failure_metadata(failure);
    draft
}

fn build_external_api_failure_metadata(failure: &ExternalApiFailureDraft) -> Value {
    let mut metadata = json!({
        "provider": failure.provider,
        "endpoint": failure.endpoint,
        "operation": failure.operation,
        "failureStage": failure.failure_stage,
        "statusCode": failure.status_code,
        "statusClass": failure.status_class.unwrap_or_else(|| status_class(failure.status_code)),
        "timeout": failure.timeout,
        "retryable": failure.retryable,
        "errorMessage": truncate_field(failure.error_message.as_str(), 1_000),
        "occurredAt": current_utc_iso_text(),
    });

    if let Some(latency_ms) = failure.latency_ms {
        metadata["latencyMs"] = json!(latency_ms);
    }
    if let Some(prompt_chars) = failure.prompt_chars {
        metadata["promptChars"] = json!(prompt_chars);
    }
    if let Some(reference_image_count) = failure.reference_image_count {
        metadata["referenceImageCount"] = json!(reference_image_count);
    }
    if let Some(image_model) = failure.image_model {
        metadata["imageModel"] = json!(image_model);
    }
    if let Some(source) = failure
        .error_source
        .as_deref()
        .map(str::trim)
        .filter(|value| !value.is_empty())
    {
        metadata["errorSource"] = json!(truncate_field(source, 1_000));
    }
    if let Some(excerpt) = failure
        .raw_excerpt
        .as_deref()
        .map(str::trim)
        .filter(|value| !value.is_empty())
    {
        metadata["rawExcerpt"] = json!(truncate_field(excerpt, 800));
    }

    metadata
}

pub(crate) fn is_retryable_external_api_failure(
    status_code: Option<u16>,
    timeout: bool,
    connect: bool,
) -> bool {
    timeout
        || connect
        || status_code.is_some_and(|status| {
            status == StatusCode::TOO_MANY_REQUESTS.as_u16()
                || status == StatusCode::REQUEST_TIMEOUT.as_u16()
                || status >= 500
        })
}

fn record_external_api_failure_otlp(failure: &ExternalApiFailureDraft) {
    crate::telemetry::record_external_api_failure(
        failure.provider,
        failure.failure_stage,
        failure
            .status_class
            .unwrap_or_else(|| status_class(failure.status_code)),
        failure.retryable,
    );

    tracing::error!(
        provider = failure.provider,
        endpoint = %failure.endpoint,
        operation = %failure.operation,
        failure_stage = failure.failure_stage,
        status_code = failure.status_code,
        status_class = failure.status_class.unwrap_or_else(|| status_class(failure.status_code)),
        timeout = failure.timeout,
        retryable = failure.retryable,
        latency_ms = failure.latency_ms,
        prompt_chars = failure.prompt_chars,
        reference_image_count = failure.reference_image_count,
        image_model = failure.image_model,
        error = %failure.error_message,
        "外部 API 调用失败"
    );
}

fn status_class(status_code: Option<u16>) -> &'static str {
    match status_code {
        Some(100..=199) => "1xx",
        Some(200..=299) => "2xx",
        Some(300..=399) => "3xx",
        Some(400..=499) => "4xx",
        Some(500..=599) => "5xx",
        Some(_) => "unknown",
        None => "transport",
    }
}

fn audit_request_context() -> crate::request_context::RequestContext {
    crate::request_context::RequestContext::new(
        format!("external-api-audit-{}", Uuid::new_v4()),
        "external-api audit".to_string(),
        std::time::Duration::ZERO,
        false,
    )
}

fn truncate_field(value: &str, max_chars: usize) -> String {
    value.chars().take(max_chars).collect()
}

fn current_utc_iso_text() -> String {
    shared_kernel::format_rfc3339(OffsetDateTime::now_utc())
        .unwrap_or_else(|_| "1970-01-01T00:00:00Z".to_string())
}

#[cfg(test)]
mod tests {
    use serde_json::Value;

    use super::*;

    #[test]
    fn external_api_failure_tracking_draft_uses_module_scope_and_safe_metadata() {
        let draft = build_external_api_failure_tracking_draft(
            &ExternalApiFailureDraft::new(
                "vector-engine",
                "https://vector.example/v1/images/generations",
                "拼图 UI 背景图生成失败",
                "upstream_status",
                "上游 429",
            )
            .with_status_code(Some(429))
            .with_retryable(true)
            .with_latency_ms(Some(1234))
            .with_prompt_chars(Some(88))
            .with_reference_image_count(Some(2))
            .with_image_model(Some("gpt-image-2-all")),
        );

        assert_eq!(draft.event_key, EXTERNAL_API_FAILURE_EVENT_KEY);
        assert_eq!(draft.scope_kind, RuntimeTrackingScopeKind::Module);
        assert_eq!(draft.scope_id, "vector-engine");
        assert_eq!(draft.module_key, Some(EXTERNAL_API_AUDIT_MODULE_KEY));

        let metadata = draft.metadata;
        assert_eq!(metadata["provider"], "vector-engine");
        assert_eq!(metadata["statusCode"], 429);
        assert_eq!(metadata["statusClass"], "4xx");
        assert_eq!(metadata["retryable"], true);
        assert_eq!(metadata["latencyMs"], 1234);
        assert_eq!(metadata["promptChars"], 88);
        assert_eq!(metadata["referenceImageCount"], 2);
        assert_eq!(metadata["imageModel"], "gpt-image-2-all");
        assert!(matches!(metadata["occurredAt"], Value::String(_)));
    }

    #[test]
    fn retryable_classification_keeps_transport_and_overload_failures_actionable() {
        assert!(is_retryable_external_api_failure(None, true, false));
        assert!(is_retryable_external_api_failure(None, false, true));
        assert!(is_retryable_external_api_failure(Some(429), false, false));
        assert!(is_retryable_external_api_failure(Some(502), false, false));
        assert!(!is_retryable_external_api_failure(Some(400), false, false));
    }

    #[test]
    fn app_error_status_class_can_override_successful_upstream_status() {
        let draft = build_external_api_failure_tracking_draft(
            &ExternalApiFailureDraft::new(
                "vector-engine",
                "https://cdn.example/generated.png",
                "下载生成图片",
                "image_download",
                "下载生成图片失败",
            )
            .with_status_code(Some(200))
            .with_optional_status_class(Some(app_error_status_class(StatusCode::BAD_GATEWAY))),
        );

        assert_eq!(draft.metadata["statusCode"], 200);
        assert_eq!(draft.metadata["statusClass"], "5xx");
    }
}