vespera_macro 0.3.1

use proc_macro2::Span;
use quote::quote;
use vespera_core::route::HttpMethod;

use crate::{
    metadata::{CollectedMetadata, CronMetadata},
    method::http_method_to_token_stream,
};

use super::docs::{REDOC_HTML, SWAGGER_UI_HTML, generate_docs_route_tokens};

/// Build `crate::<module_path>::<function_name>` as a `syn::Path`.
/// Empty segments inside `module_path` (from accidental `::` doubling)
/// are dropped, matching the existing behaviour of both call sites.
fn crate_path_to(module_path: &str, function_name: &str) -> syn::Path {
    let mut segments: syn::punctuated::Punctuated<syn::PathSegment, syn::Token![::]> =
        syn::punctuated::Punctuated::new();
    segments.push(syn::PathSegment {
        ident: syn::Ident::new("crate", Span::call_site()),
        arguments: syn::PathArguments::None,
    });
    segments.extend(module_path.split("::").filter_map(|s| {
        if s.is_empty() {
            None
        } else {
            Some(syn::PathSegment {
                ident: syn::Ident::new(s, Span::call_site()),
                arguments: syn::PathArguments::None,
            })
        }
    }));
    segments.push(syn::PathSegment {
        ident: syn::Ident::new(function_name, Span::call_site()),
        arguments: syn::PathArguments::None,
    });
    syn::Path {
        leading_colon: None,
        segments,
    }
}

/// Generate cron scheduler spawn code from collected cron metadata.
fn generate_cron_scheduler_code(cron_jobs: &[CronMetadata]) -> proc_macro2::TokenStream {
    if cron_jobs.is_empty() {
        return quote!();
    }

    let job_additions: Vec<proc_macro2::TokenStream> = cron_jobs
        .iter()
        .map(|cron| {
            let expression = &cron.expression;
            let module_path = &cron.module_path;
            let function_name = &cron.function_name;

            // Build the full path: crate::module::function
            let call_path = crate_path_to(module_path, function_name);

            let err_create = format!("vespera: failed to create cron job '{function_name}'");
            let err_add = format!("vespera: failed to add cron job '{function_name}'");

            quote! {
                // A cron expression is compile-time validated (vespera_macro/cron
                // feature), so `new_async` failing here is a runtime library/env
                // condition, not user error — log it and skip THIS job rather than
                // `.expect()`-panicking the whole scheduler task (which tokio would
                // swallow as a silent `JoinError`, hiding the failure entirely).
                match vespera::tokio_cron_scheduler::Job::new_async(#expression, |_uuid, _l| {
                    Box::pin(async move {
                        #call_path().await;
                    })
                }) {
                    Ok(__vespera_job) => {
                        if let Err(__vespera_err) =
                            __vespera_cron_scheduler.add(__vespera_job).await
                        {
                            eprintln!("{}: {__vespera_err}", #err_add);
                        }
                    }
                    Err(__vespera_err) => eprintln!("{}: {__vespera_err}", #err_create),
                }
            }
        })
        .collect();

    quote! {
        vespera::tokio::spawn(async move {
            // Scheduler setup runs in a detached `tokio::spawn` task: a panic here
            // would be swallowed as a silent `JoinError`, so log + bail instead of
            // `.expect()` so a scheduler-init failure is observable, not invisible.
            let mut __vespera_cron_scheduler =
                match vespera::tokio_cron_scheduler::JobScheduler::new().await {
                    Ok(__vespera_sched) => __vespera_sched,
                    Err(__vespera_err) => {
                        eprintln!("vespera: failed to create cron scheduler: {__vespera_err}");
                        return;
                    }
                };
            #(#job_additions)*
            if let Err(__vespera_err) = __vespera_cron_scheduler.start().await {
                eprintln!("vespera: failed to start cron scheduler: {__vespera_err}");
                return;
            }
            // Keep the scheduler alive for the process lifetime.
            ::std::future::pending::<()>().await;
        });
    }
}

/// Generate Axum router code from collected metadata
#[allow(clippy::too_many_lines)]
pub fn generate_router_code(
    metadata: &CollectedMetadata,
    docs_url: Option<&str>,
    redoc_url: Option<&str>,
    spec_tokens: Option<proc_macro2::TokenStream>,
    merge_apps: &[syn::Path],
    cron_jobs: &[CronMetadata],
) -> proc_macro2::TokenStream {
    let mut router_nests = Vec::new();

    for route in &metadata.routes {
        let Ok(http_method) = HttpMethod::try_from(route.method.as_str()) else {
            let message = format!(
                "vespera: route '{}' has unsupported HTTP method '{}'. Supported methods are GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS.",
                route.path, route.method
            );
            router_nests.push(syn::Error::new(Span::call_site(), message).to_compile_error());
            continue;
        };
        let method_path = http_method_to_token_stream(http_method);
        let path = &route.path;
        let module_path = &route.module_path;
        let function_name = &route.function_name;

        let call_path = crate_path_to(module_path, function_name);
        router_nests.push(quote!(
            .route(#path, #method_path(#call_path))
        ));
    }

    // Check if we need to merge specs at runtime
    let has_merge = !merge_apps.is_empty();

    // Generate merge code once, reuse in both docs_url and redoc_url routes
    let merge_spec_code: Vec<_> = merge_apps
        .iter()
        .map(|app_path| {
            quote! {
                if let Ok(other) = vespera::serde_json::from_str::<vespera::OpenApi>(#app_path::OPENAPI_SPEC) {
                    merged.merge(other);
                }
            }
        })
        .collect();

    let docs_spec_expr = if has_merge {
        quote! { __vespera_merged_spec() }
    } else {
        quote! { __VESPERA_SPEC }
    };

    if let Some(docs_url) = docs_url {
        router_nests.push(generate_docs_route_tokens(
            docs_url,
            SWAGGER_UI_HTML,
            &docs_spec_expr,
        ));
    }

    if let Some(redoc_url) = redoc_url {
        router_nests.push(generate_docs_route_tokens(
            redoc_url,
            REDOC_HTML,
            &docs_spec_expr,
        ));
    }

    let needs_spec_const = spec_tokens.is_some() && (docs_url.is_some() || redoc_url.is_some());
    let cron_code = generate_cron_scheduler_code(cron_jobs);

    if needs_spec_const {
        let spec_expr = spec_tokens.unwrap();
        if merge_apps.is_empty() {
            quote! {
                {
                    const __VESPERA_SPEC: &str = #spec_expr;
                    #cron_code
                    vespera::axum::Router::new()
                        #( #router_nests )*
                }
            }
        } else {
            quote! {
                {
                    const __VESPERA_SPEC: &str = #spec_expr;
                    fn __vespera_merged_spec() -> &'static str {
                        static MERGED_SPEC: std::sync::OnceLock<String> = std::sync::OnceLock::new();
                        MERGED_SPEC.get_or_init(|| {
                            // The base spec is Vespera-generated and expected to parse; on the
                            // unreachable drift where parse or re-serialization fails, fall back
                            // to serving the un-merged base spec instead of panicking inside this
                            // request handler — the docs page still renders.
                            let Ok(mut merged) =
                                vespera::serde_json::from_str::<vespera::OpenApi>(__VESPERA_SPEC)
                            else {
                                return __VESPERA_SPEC.to_string();
                            };
                            #(#merge_spec_code)*
                            vespera::serde_json::to_string(&merged)
                                .unwrap_or_else(|_| __VESPERA_SPEC.to_string())
                        })
                    }
                    #cron_code
                    vespera::VesperaRouter::new(
                        vespera::axum::Router::new()
                            #( #router_nests )*,
                        vec![#( #merge_apps::router ),*]
                    )
                }
            }
        }
    } else if merge_apps.is_empty() {
        if cron_jobs.is_empty() {
            quote! {
                vespera::axum::Router::new()
                    #( #router_nests )*
            }
        } else {
            quote! {
                {
                    #cron_code
                    vespera::axum::Router::new()
                        #( #router_nests )*
                }
            }
        }
    } else {
        // When merging apps, return VesperaRouter which defers the merge
        // until with_state() is called. This is necessary because Axum requires
        // merged routers to have the same state type.
        if cron_jobs.is_empty() {
            quote! {
                vespera::VesperaRouter::new(
                    vespera::axum::Router::new()
                        #( #router_nests )*,
                    vec![#( #merge_apps::router ),*]
                )
            }
        } else {
            quote! {
                {
                    #cron_code
                    vespera::VesperaRouter::new(
                        vespera::axum::Router::new()
                            #( #router_nests )*,
                        vec![#( #merge_apps::router ),*]
                    )
                }
            }
        }
    }
}

#[cfg(test)]
mod tests;