import dbg from "debug";
import * as FS from "fs";
import Color from "chalk";
import * as Path from "path";
import tokenize, { TokenizerError } from "./tokenizer";
import parse, { Parsed, ParserError } from "./parser";
import get_ir, { IR } from "./ir";
import compile, { CompileTarget } from "./compile";
import { ESMTypescriptTarget, NodeJSTypescriptTarget } from "./targets/typescript";

const log = dbg("app");


const Targets = new Map<string,typeof CompileTarget>();

Targets.set("ts-esm", ESMTypescriptTarget)
Targets.set("ts-node", NodeJSTypescriptTarget)


function indexToLineAndCol(src: string, index: number) {
   let line = 1;
   let col = 1;
   for (let i = 0; i < index; i++) {
      if (src.charAt(i) === "\n") {
         line++;
         col = 1;
      } else {
         col++;
      }
   }

   return { line, col };
}

const fileCache = new Map<string, string>();
function getFile(name: string) {
   if (fileCache.has(name)) return fileCache.get(name);
   else {
      try {
         const data = FS.readFileSync(name, "utf-8");
         fileCache.set(name, data);
         return data;
      } catch (err) {
         printError(new Error(`Cannot open file ${name};`), null, 0);
      }
   }
   return undefined;
}

function printError(err: Error, file: string | null, idx: number) {
   let loc = { line: 0, col: 0 };
   if (file != null) {
      const data = getFile(file);
      if (data) loc = indexToLineAndCol(data, idx);
   }

   console.error(`${Color.red("ERROR: at")} ${file}:${loc.line}:${loc.col}`);
   console.error("   ", err.message);
   log(err.stack);
}

export type Target = {
   type: string;
   output: string;
};

export type CompileOptions = {
   input: string;
   targets: Target[];
   emitDefinitions?: string;
};

type ProcessContext = {
   options: CompileOptions;
   processedFiles: Set<string>;
};

function processFile(ctx: ProcessContext, file: string): Parsed | null {
   file = Path.resolve(file);
   if (ctx.processedFiles.has(file)) {
      log("Skipping file %s since it has already be processed", file);
      return null;
   }
   log("Processing file %s", file);

   const content = getFile(file);
   if (!content) throw new Error("Could not open file " + file);
   try {
      log("Tokenizing %s", file);
      const tokens = tokenize(content);
      log("Parsing %s", file);
      const parsed = parse(tokens, file);

      log("Resolving imports of %s", file);
      let resolved = parsed
         .map((statement) => {
            if (statement.type == "import") {
               const base = Path.dirname(file);
               const resolved = Path.resolve(Path.join(base, statement.path));
               return processFile(ctx, resolved);
            } else {
               return statement;
            }
         })
         .filter((e) => !!e)
         .flat(1) as Parsed;
      return resolved;
   } catch (err) {
      if (err instanceof TokenizerError) {
         printError(err, file, err.index);
      } else if (err instanceof ParserError) {
         printError(err, file, err.token.startIdx);
      } else {
         throw err;
      }

      return null;
   }
}

export default function startCompile(options: CompileOptions) {
   const ctx = {
      options,
      processedFiles: new Set(),
   } as ProcessContext;

   let ir: IR | undefined = undefined;
   if(options.input.endsWith(".json")) {
      ir = JSON.parse(FS.readFileSync(options.input, "utf-8"));
   } else {
      const parsed = processFile(ctx, options.input);
      // console.log(([...parsed].pop() as any).functions)
      if(!parsed)
         throw new Error("Error compiling: Parse output is undefined!");
      
      ir = get_ir(parsed);
   }

   if(!ir)
      throw new Error("Error compiling: Cannot get IR");

   if(options.emitDefinitions) {
      FS.writeFileSync(options.emitDefinitions, JSON.stringify(ir));
   }

   options.targets.forEach(target => {
      const tg = Targets.get(target.type) as any
      if(!tg) {
         console.log(Color.red("ERROR:"), "Target not supported!");
         return;
      }
      compile(ir, new tg(target.output)); //TODO: implement
   })
}