package org.simantics.scl.compiler.errors;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

import gnu.trove.list.array.TIntArrayList;

public class CompilationErrorFormatter {

    public static int[] rows(Reader reader) throws IOException {
        TIntArrayList rows = new TIntArrayList();
        rows.add(0);
        
        int i=0;
        while(true) {
            ++i;
            int c = reader.read();
            if(c < 0)
                break;
            if(c == '\n')
                rows.add(i);
        }
        reader.close();
        return rows.toArray();
    }
    
    public static int lineNumber(int[] rows, int location) {
        if(location < 0)
            return 1;
        if(location >= rows[rows.length-1])
            return rows.length;
        int a = 0;
        int b = rows.length-1;
        while(b-a > 1) {
            int c = (a+b)/2;
            if(rows[c] <= location)
                a = c;
            else
                b = c;
        }
        return a+1;
    }
    
    private static String locationToString(int[] rows, int location) {
        if(location == -1)
            return "?";
        if(location >= rows[rows.length-1])
            return rows.length + ":" + (location - rows[rows.length-1] + 1);
        int a = 0;
        int b = rows.length-1;
        while(b-a > 1) {
            int c = (a+b)/2;
            if(rows[c] <= location)
                a = c;
            else
                b = c;
        }
        return (a+1) + ":" + (location - rows[a] + 1);
    }
    
    public static String toString(String source, CompilationError[] errors) {
        return toString(new StringReader(source), errors);
    }
    
    public static String toString(Reader source, CompilationError[] errors) {
        int[] rows;
        try {
            if(source != null)
                rows = rows(source);
            else
                rows = new int[] {0};
        } catch(IOException e) {
            rows = new int[] {0};
        }
        StringBuilder b = new StringBuilder();
        boolean first = true;
        for(CompilationError error : errors) {
            if(first)
                first = false;
            else
                b.append('\n');
            b.append(locationToString(rows, Locations.beginOf(error.location)) + "-" + 
                    locationToString(rows, Locations.endOf(error.location)) + ": " +
                    error.description);
        }
        return b.toString();
    }

    public static String toString(CompilationError[] errors) {
        return toString((Reader)null, errors);
    }
}