import org.cuelang.cue.*;

public class HandleErrors {
    public static void main(String[] args) {
        var ctx = new CueContext();

        try {
            var v = ctx.compile("x: {"); // Syntax error.
        } catch (CueError e) {
            System.out.println("## Catch block #1");
            System.out.println(e.getMessage());
        }

        try {
            var v = ctx.compile("a: b: c: d: 1");
            var v1 = v.lookup("x"); // Invalid path.
        } catch (CueError e) {
            System.out.println("\n## Catch block #2");
            System.out.println(e.getMessage());
        }

        try {
            var v = ctx.compile("123");
            var s = v.getString(); // Not a string.
        } catch (CueError e) {
            System.out.println("\n## Catch block #3");
            System.out.println(e.getMessage());
        }

        try {
            var v = ctx.compile("{ x: bool, y: 42 }");
            var s = v.getJSON(); // x isn't a concrete value.
        } catch (CueError e) {
            System.out.println("\n## Catch block #4");
            System.out.println(e.getMessage());
        }

        try {
            // Unification of valid CUE never throws an error. The result is
            // always defined, with a value of _|_ (bottom) if unification failed.
            System.out.println("\n## Unification #1");
            var a  = ctx.compile("A: true");
            var b  = ctx.compile("A: true");
            var ab = a.unify(b);
            System.out.println("ab is: " + ab.getJSON());
            System.out.println("printError() reports: ");
            printError(ab);

            System.out.println("\n## Unification #2");
            var x  = ctx.compile("B: 1");
            var y  = ctx.compile("B: 2");
            var xy = x.unify(y);
            System.out.println("printError() reports: ");
            printError(xy);
        } catch (CueError e) {
            System.out.println("## Catch block #5");
        }
    }

    static void printError(Value v) {
        // To check if a unification resulted in an error use the error() method on Value.
        // error() returns a Result, which can be Ok (success) or Err (an error occurred).
        switch (v.error()) {
            case Result.Ok<Value, String> ok -> System.out.println("ok");
            case Result.Err<Value, String> err -> System.out.println(err.err());
        }
    }
}