module mail.headers;

import std.conv;
import std.algorithm;
import std.string;
import std.array;

debug import std.stdio;

enum maxLen = 78;

string norm(string)(string key)
{
    return map!("a.capitalize()")(key.split("-")).join("-");
}

struct Headers
{
    private
    {
        struct Header
        {
            string key;
            string value;
        }

        Header[] _headers;
    }

    this(in Headers rsh)
    {
        _headers ~= rsh._headers.idup;
    }

    string[] all(string key) const pure
    {
        auto nKey = key.norm;
        string[] result;
        foreach (h; _headers)
        {
            if (h.key == nKey)
            {
                result ~= h.value;
            }
        }
        return result;
    }

    void update(string[string] values) pure
    {
        foreach (k, ref v; values)
        {
            opIndexAssign(v, k);
        }
    }

    string opIndex(string key) pure const
    {
        auto nKey = key.norm;
        auto val = "";
        foreach (h; _headers)
        {
            if (h.key == nKey)
            {
                val = h.value;
                break;
            }
        }
        return val;
    }

    string get(string key, lazy string defVal = null) pure const
    {
        auto nKey = key.norm;
        foreach (h; _headers)
        {
            if (h.key == nKey)
            {
                return h.value;
            }
        }
        return defVal;
    }

    void opIndexAssign(ulong val, string key) pure
    {
        opIndexAssign(to!string(val), key);
    }

    void opIndexAssign(string[] val, string key) pure
    {
        opIndexAssign(val.join(","), key);
    }

    void opIndexAssign(string val, string key) pure
    {
        auto nKey = key.norm;
        foreach (h; _headers)
        {
            if (h.key == nKey)
            {
                h.value = val;
                return;
            }
        }
        _headers ~= Header(nKey, val);
    }

    void add(string key, string val) pure
    {
        _headers ~= Header(key.norm, val);
    }

    void toString(scope void delegate(const(char)[]) sink) const
    {
        foreach (item; _headers)
        {
            // TODO: Folding
            sink(item.key);
            sink(": ");
            sink(item.value);
            sink("\r\n");
        }
        sink("\r\n");
    }

    void parse(string data) pure
    {
        string key;
        string[] val;
        void save()
        {
            add(key, val.join(" "));
            val.length = 0;
        }

        auto lines = data.split("\n");
        while (lines.length)
        {
            auto tmp = lines.front.strip.findSplit(":");
            key = tmp[0];
            val ~= tmp[2].strip;
            lines.popFront;
            while (lines.length && (lines.front.startsWith("\t") || lines.front.startsWith(" ")))
            {
                val ~= lines.front.strip;
                lines.popFront;
            }
            save();
        }
    }
}

unittest
{
    Headers h;

    h["key1"] = "val1";
    h["key2"] = "val2";

    assert(h.get("key1") == "val1");
    assert(h["key2"] == "val2");

    h.add("key2", "val2_2");
    assert(h["key2"] == "val2");
    assert(h.all("key2") == ["val2", "val2_2"]);

}