cartographer/map_api.lua

local map_data, chunk, scanner, marker_lookup = ...;

local Map = {};
Map.__index = Map;

for _,loaded_map in ipairs(map_data.maps) do
    setmetatable(loaded_map, Map);
end

function Map.resize(self, w, h)
    if w >= self.w and h >= self.h then
        self.w = w;
        self.h = h;
        -- FIXME: Is this really correct? Seems questionable.
    end
end

function Map.fill_area(self, x, z, w, h)
    for i = math.max(x, self.x),math.min(x + w - 1, self.x + self.w),1 do
        for j = math.max(z, self.z),math.min(z + h - 1, self.z + self.h),1 do
            self.fill[(i - self.x) + ((j - self.z) * self.w)] = self.detail;
        end
    end
end

function Map.set_marker(self, x, z, marker)
    if x < self.x or x > self.x + self.w or z < self.z or z > self.z + self.h then
        return;
    end

    if not self.markers[x] then
        self.markers[x] = {
            [z] = marker,
        };
    else
        self.markers[x][z] = marker;
    end
end

function Map.get_marker(self, x, z)
    if x < self.x or x > self.x + self.w or z < self.z or z > self.z + self.h or not self.markers[x] then
        return nil;
    end

    return self.markers[x][z];
end

-- Fill in the local area of a map around a position
-- id: A map ID
-- x: The x position, in world coordinates
-- z: The z position, in world coordinates
function Map.fill_local(self, x, z)
    x, z = self:to_coordinates(x, z);

    -- TODO: Adjust size to match map scale
    if x >= self.x - 2 and x <= self.x + self.w + 1 and z >= self.z - 2 and z <= self.z + self.h + 1 then
        self:fill_area(x - 2, z - 2, 5, 5);
    end
end

-- Convert a position in world coordinates to the given map's coordinate system
-- self: The map to use as reference
-- x: The x position, in world coordinates
-- z: The z position, in world coordinates
--
-- Returns The converted x and z coordinates
function Map.to_coordinates(self, x, z)
    if self.scale == 0 then
        return chunk.to(x), chunk.to(z);
    end

    return math.floor(chunk.to(x) / self.scale + 0.5), math.floor(chunk.to(z) / self.scale + 0.5);
end

function Map.is_filled(self, x, z)
    return self.fill[(x - self.x) + ((z - self.z) * self.w)] ~= nil;
end

local maps = {
    create = function(x, z, w, h, filled, detail, scale)
        local id = map_data.next_map_id;

        local map = {
            id = id,
            x = x,
            z = z,
            w = w,
            h = h,
            detail = detail,
            scale = scale,
            fill = {},
            markers = {},
        };
        setmetatable(map, Map);

        map_data.maps[id] = map;
        if filled then
            map:fill(map, x, z, w, h);
        end

        map_data.next_map_id = map_data.next_map_id + 1;

        return id;
    end,

    get = function(id)
        return map_data.maps[id];
    end,
}

-- Periodically-called function to fill in maps and queue chunks for manual
-- scanning
local function fill_loop()
    -- Fill in all player-held maps
    for _,p in ipairs(minetest.get_connected_players()) do
        local inventory = p:get_inventory();
        local pos = p:get_pos();
        if pos.y > -10 then
            for i = 1,inventory:get_size("main") do
                local stack = inventory:get_stack("main", i);
                local map = maps.get(stack:get_meta():get_int("cartographer:map_id"));

                if map then
                    map:fill_local(pos.x, pos.z);
                end
            end
            for i = -2,2 do
                for j = -2,2 do
                    local adjusted_pos = {
                        x = pos.x + chunk.from(i),
                        y = pos.y,
                        z = pos.z + chunk.from(j),
                    }
                    scanner.queue_region(adjusted_pos);
                end
            end
        end
    end

    for _ = 1,10 do
        scanner.scan_regions();
    end
    minetest.after(5, fill_loop);
end
minetest.after(5, fill_loop);

-- Format marker ids to allow their use as formspec element ids.
-- We're mostly concerned with guarding against the : character because it is
-- common for ids and has an alternate meaning in formspecs.
-- id: The id to format
--
-- Returns the formatted id
local function format_marker_id(id)
    return id:gsub(":", "_");
end

-- Find the marker data for a given id
-- id: The id to search for
--
-- Returns the marker data, or nil if not found
function cartographer.get_marker_data(id)
    if not id then
        return nil;
    end

    id = format_marker_id(id);
    for _,marker in pairs(marker_lookup) do
        if marker.id == id then
            return marker;
        end
    end

    return nil;
end

-- Register a marker with textures to display
-- id: A string containing the id of the marker
-- name: A string containing the displayedname of the marker
-- textures: A table of texture names.
--           These should correspond with detail levels,
--           any detail level past the length of the table will return the last texture
function cartographer.register_marker(id, name, textures)
    if not id then
        return nil;
    end

    id = format_marker_id(id);
    local existing_marker = cartographer.get_marker_data(id);
    if existing_marker then
        existing_marker.name = name;
        existing_marker.textures = textures;
    else
        marker_lookup[#marker_lookup+1] = {
            id = id,
            name = name,
            textures = textures,
        };
    end
end

-- Get an entry from a list for a given detail level
-- textures: An array of textures
-- detail: The detail level
--
-- Returns the entry at detail, or the last entry if detail is out-of-bounds
function cartographer.detail_texture(textures, detail)
    return textures[math.min(detail, #textures)];
end

-- Get the texture name (minus extension) for the given marker and detail level.
-- id: A string containing the marker id
-- detail: The detail level
-- Returns a string with a texture name, or nil if no matching marker was found.
function cartographer.get_marker_texture(id, detail)
    if not id then
        return nil;
    end

    id = format_marker_id(id);
    local marker = cartographer.get_marker_data(id);

    if marker then
        return marker.textures[math.min(detail, #marker.textures)];
    end

    return nil;
end

return maps;