use crate::rtlil::{RtlilWrite, SigSpec};

#[derive(Debug)]
pub struct Process {
    pub id: String,
    pub root_case: CaseRule,
    pub sync_rules: Vec<SyncRule>,
}

#[derive(Debug)]
pub struct CaseRule {
    pub assign: Vec<(SigSpec, SigSpec)>,
    pub switches: Vec<SwitchRule>,
}

#[derive(Debug)]
pub struct SwitchRule {
    pub signal: SigSpec,
    pub cases: Vec<(SigSpec, CaseRule)>,
}

#[derive(Debug)]
pub struct SyncRule {
    pub cond: SyncCond,
    pub assign: Vec<(SigSpec, SigSpec)>,
}

#[derive(Debug)]
pub enum SyncCond {
    Always,
    Init,
    Posedge(SigSpec),
    Negedge(SigSpec),
}

impl RtlilWrite for Process {
    fn write_rtlil(&self, writer: &mut super::ILWriter) {
        writer.write_line(&format!("process {}", self.id));
        writer.indent();
        self.root_case.write_rtlil(writer);
        writer.write_iter(&self.sync_rules);
        writer.dedent();
        writer.write_line("end");
    }
}

impl RtlilWrite for CaseRule {
    fn write_rtlil(&self, writer: &mut super::ILWriter) {
        for assign in &self.assign {
            writer.write_line(&format!("assign {} {}", assign.0, assign.1));
        }
        writer.write_iter(&self.switches);
    }
}

impl RtlilWrite for SwitchRule {
    fn write_rtlil(&self, writer: &mut super::ILWriter) {
        writer.write_line(&format!("switch {}", self.signal));
        writer.indent();
        for case in &self.cases {
            writer.write_line(&format!("case {}", case.0));
            writer.indent();
            case.1.write_rtlil(writer);
            writer.dedent();
        }
        writer.dedent();
        writer.write_line("end");
    }
}

impl RtlilWrite for SyncRule {
    fn write_rtlil(&self, writer: &mut super::ILWriter) {
        let sync_expr = match &self.cond {
            SyncCond::Always => "always".to_owned(),
            SyncCond::Init => "always".to_owned(),
            SyncCond::Posedge(sig) => format!("posedge {}", sig),
            SyncCond::Negedge(sig) => format!("negedge {}", sig),
        };
        writer.write_line(&format!("sync {}", sync_expr));
        writer.indent();

        for update in &self.assign {
            writer.write_line(&format!("update {} {}", update.0, update.1));
        }
        writer.dedent();
    }
}