import std.stdio;
import std.string;
import std.conv;

import parser;
import dbg;

enum ObjType {
    FUNCTION,
    SCRIPT,
}

abstract class Obj {
    ObjType type;
}

class Function : Obj {
    Chunk chunk;
    int arity;
    string name;
    ObjType type;

    this(ObjType type, string name = "") {
        this.type = type;
        this.chunk = new Chunk();
        this.arity = 0;
        this.name = name;
    }

    override string toString() {
        if (type == ObjType.SCRIPT) {
            return "<neb>";
        } else {
            return format("<fn %s>", name);
        }
    }
}

enum SeqType {
    LIST,
    STRING,
}

abstract class Seq {
    SeqType type;
    abstract Value first();
    abstract Seq rest();
    abstract int length();
}

class String : Seq {
    string str;

    this(Value value) {
        this.str = value.as.str;
    }

    this(string str) {
        this.str = str;
    }

    override Value first() {
        return makeStringValue(to!string(this.str[0]));
    }

    override Seq rest() {
        return new String(this.str[1..$]);
    }

    override int length() {
        return to!int(str.length);
    }

    override string toString() {
        return format("\"%s\"", this.str);
    }
}

class List : Seq {
    Value[] inner;

    this(int length) {
        this.inner = new Value[length];
        this.type = SeqType.LIST;
    }

    void addItemAtIndex(Value item, int idx) {
        this.inner[idx] = item;
    }

    override Value first() {
        return this.inner[0];  // this fails on NIL
    }

    override Seq rest() {
        List ret = new List(to!int(this.inner.length) - 1);
        for (int i = 1; i < this.inner.length; i++) {
            ret.addItemAtIndex(this.inner[i], i - 1);
        }
        return ret;
    }

    override int length() {
        return to!int(this.inner.length);
    }

    override string toString() {
        return format("list ('%s' + %d)", printableValue(this.inner[0]), this.inner.length - 1);
    }
}

enum OpCode {
    OP_ADD,
    OP_LESS,
    OP_NOT,
    OP_GREATER,
    OP_NEGATE,
    OP_RETURN,
    OP_CONSTANT,
    OP_DEF_GLOBAL,
    OP_GET_GLOBAL,
    OP_SET_GLOBAL,
    OP_DEF_LOCAL,
    OP_GET_LOCAL,
    OP_SET_LOCAL,
    OP_POP,
    OP_POPB,
    OP_POP_SCOPE,
    OP_SUBTRACT,
    OP_NIL,

    OP_JUMP,
    OP_JUMP_IF_FALSE,
    OP_JUMP_IF_TRUE,

    OP_CALL,

    OP_LIST,

    OP_CONCAT,  // No?

    OP_FIRST,   // No?
    OP_REST,
    OP_LENGTH,

    OP_TYPE_CHECK_NUMBER,
    OP_TYPE_CHECK_BOOLEAN,
    OP_TYPE_CHECK_STRING,
    OP_TYPE_CHECK_LIST,
    OP_TYPE_CHECK_SEQ,
}

class Chunk {
    int count = 0;
    ubyte[] code;
    int[] lines;
    Value[] constants;

    //int writeOp(OpCode opCode, int line) {
    int writeOp(ubyte opCode, int line) {
        this.code ~= opCode;
        this.lines ~= line;
        this.count++;
        assert(this.code.length == count);
        assert(this.lines.length == count);
        return count;
    }

    int addConstant(Value value) {
        this.constants ~= value;
        return to!int(this.constants.length - 1);
    }

}