use crate::syntax::{ast::App, Context};
use crate::{analyze::Analysis, codegen::util};
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;

#[allow(clippy::too_many_lines)]
pub fn codegen(ctxt: Context, app: &App, analysis: &Analysis) -> TokenStream2 {
    let mut items = vec![];
    let mut module_items = vec![];
    let mut fields = vec![];
    let mut values = vec![];
    // Used to copy task cfgs to the whole module
    let mut task_cfgs = vec![];

    let name = ctxt.ident(app);

    match ctxt {
        Context::Init => {
            fields.push(quote!(
                /// Core peripherals
                pub core: rtic::export::Peripherals
            ));

            if app.args.peripherals {
                let device = &app.args.device;

                fields.push(quote!(
                    /// Device peripherals (PAC)
                    pub device: #device::Peripherals
                ));

                values.push(quote!(device: #device::Peripherals::steal()));
            }

            fields.push(quote!(
                /// Critical section token for init
                pub cs: rtic::export::CriticalSection<'a>
            ));

            values.push(quote!(cs: rtic::export::CriticalSection::new()));

            values.push(quote!(core));
        }

        Context::Idle | Context::HardwareTask(_) | Context::SoftwareTask(_) => {}
    }

    if ctxt.has_local_resources(app) {
        let ident = util::local_resources_ident(ctxt, app);

        module_items.push(quote!(
            #[doc(inline)]
            pub use super::#ident as LocalResources;
        ));

        fields.push(quote!(
            /// Local Resources this task has access to
            pub local: #name::LocalResources<'a>
        ));

        values.push(quote!(local: #name::LocalResources::new()));
    }

    if ctxt.has_shared_resources(app) {
        let ident = util::shared_resources_ident(ctxt, app);

        module_items.push(quote!(
            #[doc(inline)]
            pub use super::#ident as SharedResources;
        ));

        fields.push(quote!(
            /// Shared Resources this task has access to
            pub shared: #name::SharedResources<'a>
        ));

        values.push(quote!(shared: #name::SharedResources::new()));
    }

    let doc = match ctxt {
        Context::Idle => "Idle loop",
        Context::Init => "Initialization function",
        Context::HardwareTask(_) => "Hardware task",
        Context::SoftwareTask(_) => "Software task",
    };

    let v = Vec::new();
    let cfgs = match ctxt {
        Context::HardwareTask(t) => &app.hardware_tasks[t].cfgs,
        Context::SoftwareTask(t) => &app.software_tasks[t].cfgs,
        _ => &v,
    };

    let core = if ctxt.is_init() {
        Some(quote!(core: rtic::export::Peripherals,))
    } else {
        None
    };

    let internal_context_name = util::internal_task_ident(name, "Context");
    let exec_name = util::internal_task_ident(name, "EXEC");

    items.push(quote!(
        #(#cfgs)*
        /// Execution context
        #[allow(non_snake_case)]
        #[allow(non_camel_case_types)]
        pub struct #internal_context_name<'a> {
            #[doc(hidden)]
            __rtic_internal_p: ::core::marker::PhantomData<&'a ()>,
            #(#fields,)*
        }

        #(#cfgs)*
        impl<'a> #internal_context_name<'a> {
            #[inline(always)]
            #[allow(missing_docs)]
            pub unsafe fn new(#core) -> Self {
                #internal_context_name {
                    __rtic_internal_p: ::core::marker::PhantomData,
                    #(#values,)*
                }
            }
        }
    ));

    module_items.push(quote!(
        #(#cfgs)*
        #[doc(inline)]
        pub use super::#internal_context_name as Context;
    ));

    if let Context::SoftwareTask(..) = ctxt {
        let spawnee = &app.software_tasks[name];
        let priority = spawnee.args.priority;
        let cfgs = &spawnee.cfgs;
        // Store a copy of the task cfgs
        task_cfgs = cfgs.clone();

        let pend_interrupt = if priority > 0 {
            let device = &app.args.device;
            let enum_ = util::interrupt_ident();
            let interrupt = &analysis.interrupts.get(&priority).expect("UREACHABLE").0;
            quote!(rtic::export::pend(#device::#enum_::#interrupt);)
        } else {
            quote!()
        };

        let internal_spawn_ident = util::internal_task_ident(name, "spawn");
        let (input_args, input_tupled, input_untupled, input_ty) =
            util::regroup_inputs(&spawnee.inputs);

        // Spawn caller
        items.push(quote!(
            #(#cfgs)*
            /// Spawns the task directly
            #[allow(non_snake_case)]
            #[doc(hidden)]
            pub fn #internal_spawn_ident(#(#input_args,)*) -> Result<(), #input_ty> {
                // SAFETY: If `try_allocate` suceeds one must call `spawn`, which we do.
                unsafe {
                    if #exec_name.try_allocate() {
                        let f = #name(unsafe { #name::Context::new() } #(,#input_untupled)*);
                        #exec_name.spawn(f);
                        #pend_interrupt

                        Ok(())
                    } else {
                        Err(#input_tupled)
                    }
                }

            }
        ));

        module_items.push(quote!(
            #(#cfgs)*
            #[doc(inline)]
            pub use super::#internal_spawn_ident as spawn;
        ));
    }

    if items.is_empty() {
        quote!()
    } else {
        quote!(
            #(#items)*

            #[allow(non_snake_case)]
            #(#task_cfgs)*
            #[doc = #doc]
            pub mod #name {
                #(#module_items)*
            }
        )
    }
}