import { convertASM } from "./asm"
import { convertIR, prettyPrintIR } from "./ir"
import { parse } from "./parser"

import type { Attr, Decl, Stmt, Type, VarDecl } from "./ast"

type SymbolDefn = {
    attrs: Array<Attr>,
    name: string,
    type: Type
}

type SymbolMap = {
    [name: string]: SymbolDefn
}

// TODO: Support more than one TU
export const compile = (fileName: string, source: string): string => {
    // 1. Parse
    const ast = parse(source)

    // 2. Partition declarations and statements
    const decls = ast.filter((x): x is Decl => x.type == "decl")
    const stmts = ast.filter((x): x is Stmt => x.type == "stmt")

    // 3. Create top-level symbol map
    const symbols = processDecls(decls)

    // TODO: Support declaring types other than U8/S8
    const asmDecls = Object.values(symbols).map(symbol => `${symbol.name}:: DB`)

    // TODO: Some form of type-checking

    // 4. Generate IR
    const ir = convertIR(stmts)

    console.log("=== IR === ")
    console.log(ir.map(prettyPrintIR).join("\n"))

    // 5. Generate code
    const insns = convertASM(ir)

    let output = ''
    if (asmDecls.length > 0) {
        output += `SECTION "${fileName} Data", WRAM0\n\n`
        output += asmDecls.join("\n")
        output += "\n\n"
    }

    if (insns.length > 0) {
        output += `SECTION "${fileName} Code", ROM0\n\n`
        output += insns.join("\n")
    }

    console.log("=== ASM === ")
    return output
}

export const processDecls = (decls: Array<Decl>): SymbolMap => decls.reduce(processDecl, {})

export const processDecl = (symbols: SymbolMap, decl: Decl): SymbolMap => {
    const symbol = processVarDecl(symbols, decl)

    return {
        ...symbols,
        [symbol.name]: symbol,
    }
}

export const processVarDecl = (symbols: SymbolMap, decl: VarDecl): SymbolDefn => {
    if (typeof symbols[decl.name] !== 'undefined') {
        throw new Error(`a variable named \`${decl.name}' is already defined`)
    }

    return {
        attrs: decl.attrs,
        name: decl.name,
        type: decl.args.type,
    }
}