local update_interval = 1.31415
local compass_precision = 10 -- set to 1 to show whole number or 10 for 1 decimal
local default_waypoint_color = 0xFFFFFF
local target_above = false -- place waypoint inside the block or above it
local point_to_objects = false -- unimplemented
local point_to_liquids = true
local compass_range = 180


-- internal mod state
local player_waypoints = {} -- store a current player waypoint to see if it needs to be updated
local compass_dialog_context = {} -- store a compass item that player is editing via dialog


local function set_compass_meta_label(meta, label)
    meta:set_string("description", string.format("Waypoint compass to \"%s\"", label))
    meta:set_string("waypoint_compass:label", label)
end


local function get_compass_meta_label(meta)
    local label = meta:get_string("waypoint_compass:label")
    return label ~= "" and label or "destination"
end


local function set_compass_meta_pos(meta, pos)
    local pos_str = minetest.serialize(pos)
    meta:set_string("waypoint_compass:position", pos_str)
end


local function get_compass_meta_pos(meta)
    return minetest.deserialize(meta:get_string("waypoint_compass:position"))
end


local function set_compass_meta_color(meta, color)
    meta:set_int("waypoint_compass:color", color)
end


local function get_compass_meta_is_set(meta)
    local pos_str = meta:get_string("waypoint_compass:position")
    return pos_str ~= ""
end


local function get_compass_meta_color(meta)
    local color = meta:get_int("waypoint_compass:color")
    if color > 0 then
        return color
    else
        return default_waypoint_color
    end
end


local function set_compass_meta_owner(meta, player_name)
    meta:set_string("waypoint_compass:owner", player_name)
end


local function get_compass_meta_owner(meta)
    return meta:get_string("waypoint_compass:owner")
end


-- local function set_compass_meta_pos(meta, pos)
--     local pos_hash = minetest.hash_node_position(pos)
--     meta:set_int("waypoint_compass:position", pos_hash)
-- end


-- local function get_compass_meta_pos(meta)
--     return minetest.get_position_from_hash(meta:get_int("waypoint_compass:position"))
-- end

local function set_waypoint_at_pointed_place(itemstack, pointed_thing)
    if pointed_thing and pointed_thing.type == "node" then
        local pointed_pos = target_above and pointed_thing.above or pointed_thing.under
        local meta = itemstack:get_meta()
        meta:set_string("description", string.format("Waypoint compass %s", minetest.pos_to_string(pointed_pos)))
        set_compass_meta_pos(meta, pointed_pos)
        -- TODO change only if default?
        --set_compass_meta_label(meta, minetest.pos_to_string(pointed_pos))
        return itemstack
    end
    -- TODO handle entities?
end


-- return first thing player is pointing at
local function raycast_crosshair(player, range)
    local p_pos = player:get_pos()
    local p_eye_height = player:get_properties().eye_height
    local p_eye_pos = { x = p_pos.x, y = p_pos.y + p_eye_height, z = p_pos.z }
    local to = vector.add(p_eye_pos, vector.multiply(player:get_look_dir(), range))
    local ray = minetest.raycast(p_eye_pos, to, point_to_objects, point_to_liquids)
    local pointed_thing = ray:next()
    return pointed_thing
    -- while pointed_thing do
    --     print(pointed_thing.type, minetest.pos_to_string(pointed_thing.under))
    --     pointed_thing = ray:next()
    -- end
end


local function hide_hud_waypoint(player)
    local player_name = player:get_player_name()
    local hud_id = player_waypoints[player_name].hud_id
    player_waypoints[player_name] = nil
    player:hud_remove(hud_id)
end


local function show_hud_waypoint(player, compass_item_meta)
    local player_name = player:get_player_name()
    local waypoint_pos = get_compass_meta_pos(compass_item_meta)
    if not get_compass_meta_is_set(compass_item_meta) then
        -- do not show unset compass position
        return
    end
    -- Show this waypoint
    local waypoint_name = get_compass_meta_label(compass_item_meta)
    local waypoint_color = get_compass_meta_color(compass_item_meta)
    local hud_id = player:hud_add({
            hud_elem_type = "waypoint",
            name = waypoint_name,
            text = "m",
            precision= compass_precision,
            number = waypoint_color,
            world_pos = waypoint_pos,
    })
    -- store HUD elemnt id to remove it later
    if not player_waypoints[player_name] then
        player_waypoints[player_name] = {}
    end
    --print("hud_id add", hud_id)
    player_waypoints[player_name].pos = waypoint_pos
    player_waypoints[player_name].hud_id = hud_id
end


-- if item is a compass, then show stored waypoint
-- force - force hud update even if position is unchanged
local function update_hud_waypoint(player, itemstack, force)
    if not player:is_player() then
        return
    end
    local player_name = player:get_player_name()
    -- player is holding compass
    if (itemstack and itemstack:get_name() == "waypoint_compass:compass") then
        local meta = itemstack:get_meta()
        local waypoint_pos = get_compass_meta_pos(meta)
        -- remove different waypoint if it exists
        if player_waypoints[player_name] and
            (player_waypoints[player_name].pos ~= waypoint_pos
             or force
             or not get_compass_meta_is_set(meta)) then
            
            hide_hud_waypoint(player)
        end
        -- show new waypoint
        if not player_waypoints[player_name] then
            show_hud_waypoint(player, meta)
        end
    else
        -- not holding it anymore
        if player_waypoints[player_name] then
            hide_hud_waypoint(player)
        end
    end
end


local timer = 0
minetest.register_globalstep(function(dtime)
        timer = timer + dtime
        if timer > update_interval then
            for _,player in pairs(minetest.get_connected_players()) do
                local itemstack = player:get_wielded_item()
                update_hud_waypoint(player, itemstack)
            end
            timer = 0
        end
end)


minetest.register_on_leaveplayer(function(player, timed_out)
        local player_name = player:get_player_name()
        if player_name ~= "" then
            -- delete info about players that are left
            player_waypoints[player_name] = nil
            compass_dialog_context[player_name] = nil
        end
end)


local function coords_to_string(pos)
    -- strip "()"
    if not pos then
        pos = {x = 0, y = 0, z = 0}
    end
    return string.sub(minetest.pos_to_string(pos), 2, -2)
end


local function coords_from_string(str)
    -- numbers are separated by ","
    local tmp = {}
    for n in string.gmatch(str, "([^,]+)") do
        table.insert(tmp, n)
    end
    tmp[1] = tonumber(tmp[1]) or 0
    tmp[2] = tonumber(tmp[2]) or 0
    tmp[3] = tonumber(tmp[3]) or 0
    return {x = tmp[1], y = tmp[2], z = tmp[3]}
end


local function show_basic_dialog(itemstack, player)
    local meta = itemstack:get_meta()
    -- set focus to "close" button to preven accidental edting
    local formspec_head = "formspec_version[4]size[10,3]set_focus[close;]"
    local coords = coords_to_string(get_compass_meta_pos(meta))
    local field_coords = ("field[0.5,0.6;2.5,0.8;coords;Coords;%s]"):format(minetest.formspec_escape(coords))
    local label = get_compass_meta_label(meta)
    local field_destination = ("field[3,0.6;5,0.8;label;Label;%s]"):format(minetest.formspec_escape(label))
    local color = ("%06X"):format(get_compass_meta_color(meta))
    local field_color = ("field[8,0.6;1.5,0.8;color;Color;%s]"):format(minetest.formspec_escape(color))
    minetest.show_formspec(player:get_player_name(), "waypoint_compass:basic",
                           formspec_head ..
                           field_coords ..
                           field_destination ..
                           field_color ..
                           "button_exit[1,1.7;3,0.8;save;save]" ..
                           "button_exit[6,1.7;3,0.8;close;close]")
    local player_name = player:get_player_name()
    compass_dialog_context[player_name] = itemstack
end


local function compass_use_callback(itemstack, user, pointed_thing)
    if not (user and user:is_player()) then
        return itemstack
    end
    local meta = itemstack:get_meta()
    local owner = get_compass_meta_owner(meta)
    local player_name = user:get_player_name()
    if owner == "" then
        -- set first user as owner
        set_compass_meta_owner(meta, player_name)
    elseif owner ~= player_name then
        -- already has owner
        -- TODO show message "You are not the owner" (or maybe limit editing to color change?)
        minetest.chat_send_player(player_name, "You are not the owner of this compass. Owner is " .. owner .. ".")
        return itemstack
    end
    if user:get_player_control()["sneak"] then
        if pointed_thing.type == "nothing" then
            if user and user:is_player() then
                pointed_thing = raycast_crosshair(user, compass_range)
            end
        end
        set_waypoint_at_pointed_place(itemstack, pointed_thing)
        update_hud_waypoint(user, itemstack)
    else
        if user:is_player() then
            show_basic_dialog(itemstack, user)
        end
    end
    return itemstack
end


minetest.register_on_player_receive_fields(function(player, formname, fields)
    if formname ~= "waypoint_compass:basic" then
        return
    end
    if fields.save or (fields.key_enter_field and fields.quit) then
        local compass_item = compass_dialog_context[player:get_player_name()]
        if not compass_item then
            -- should not happen normally
            minetest.log("error","[MOD] waypoint_compass: " ..
                         player:get_player_name() ..
                         " Closed compass dialog without opening it?")
            return
        end
        local meta = compass_item:get_meta()
        
        local color = tonumber("0x"..fields.color, 16)
        if color then
            color = math.max(math.min(color, 0xFFFFFF), 0x0) -- for some reason seems to work fine without this
            set_compass_meta_color(meta, color)
        end
        
        local coords = coords_from_string(fields.coords)
        if coords then
            set_compass_meta_pos(meta, coords)
        end

        local label = fields.label
        set_compass_meta_label(meta, label)
        
        local success = player:set_wielded_item(compass_item)
        if not success then
            -- no idea why this can happen
            minetest.log("error","[MOD] waypoint_compass: " ..
                         player:get_player_name() ..
                         " Failed to swap compass after editing it")
        end
        -- assume dialog is closed and reset context
        compass_dialog_context[player:get_player_name()] = nil
        update_hud_waypoint(player, compass_item, 'force')
    end
end)


minetest.register_tool(
    "waypoint_compass:compass", {
        description = "Waypoint compass\n(sneak+place to set point)",
        --short_description = "Waypoint compass",
        inventory_image = "Waypoint_compass_inventory_image.png",
        wield_scale = {x = 0.5, y = 0.5, z = 0.5},
        range = 2.0, -- TODO what's the good range?
        on_place = function(itemstack, placer, pointed_thing)
            return compass_use_callback(itemstack, placer, pointed_thing)
        end,
        on_secondary_use = function(itemstack, user, pointed_thing)
            return compass_use_callback(itemstack, user, pointed_thing)
        end,
})