-- LUALOCALS < ---------------------------------------------------------
local include, nodecore, pairs, string, table
= include, nodecore, pairs, string, table
local string_lower
= string.lower

-- LUALOCALS > ---------------------------------------------------------
local modname = minetest.get_current_modname()

--nodecore.gametime

local cache = {}

local directions = { [0] =
    vector.new(0, 0, -1),
    vector.new(-1, 0, 0),
    vector.new(0, 0, 1),
    vector.new(1, 0, 0),
}

local down = vector.new(0, -1, 0)

local solid_drawtypes = {
    normal = true,
    glasslike_framed = true,
}

--[[
E: air
E_: other empty
Etype: territory marker of some type
Stype: a go stone of some type
W: full block wall
WE0-WE3: edge concrete
WC0-WC3: corner concrete
WB: other goban concrete
--]]
local function _check_position_uncached(pos)
    local node = minetest.get_node(pos)

    if node.name == "air" then
        return "E"
    end

    local reg_item = minetest.registered_items[node.name]

    if not reg_item then
        return "W"
    end

    if reg_item.groups and reg_item.groups.go_stone then
        return "S" .. reg_item.go_team
    end

    if reg_item.groups and reg_item.groups.go_territory_marker then
        return "E" .. reg_item.go_team
    end

    if reg_item.pattern_def then
        if reg_item.pattern_def.name == "edgy" then
            return "WE" .. node.param2
        elseif reg_item.pattern_def.name == "corny" then
            return "WC" .. node.param2
        elseif reg_item.pattern_def.name == "crossy" then
            return "WB"
        elseif reg_item.pattern_def.name == "starcrossy" then
            return "WB"
        end
    end

    if solid_drawtypes[reg_item.drawtype] and not reg_item.groups.falling_node then
        return "W"
    else
        return "E_"
    end
end

local function check_position(pos)
    local hash = minetest.hash_node_position(pos)
    if cache[hash] then
        return cache[hash]
    end

    local ret = _check_position_uncached(pos)
    cache[hash] = ret
    return ret
end

-- check for walls, physical or implied
local function edge_check(pos, dir, terminate)
    local under = check_position(pos + down)

    if under:sub(1, 1) == "W" and under:len() == 3 then
        local corner = (under:sub(2, 2) == "C")
        local edge_dir = tonumber(under:sub(3, 3))

        if (dir == edge_dir) or (corner and (dir == (edge_dir+1)%4)) then
            return true
        end
    end

    if not terminate then
        if edge_check(pos+directions[dir], (dir+2)%4, true) then
            return true
        end
    end

    return false
end

--[[
give valid neighbor directions from a position, excluding solid blocks
and also respecting borders indicated by goban concrete
--]]
local function neighbor_dirs(pos)
    local neighbors = {}
    for i,v in pairs(directions) do
        if not edge_check(pos, i) then
            if check_position(pos + directions[i]):sub(1, 1) ~= "W" then
                neighbors[#neighbors+1] = i
            end
        end
    end

    return neighbors
end

local function connected_search(pos, final_result, early_termination_filter)
    local group = {pos}
    local stones = {[minetest.hash_node_position(pos)] = pos}
    local checked = {}
    local piece = check_position(pos)

    local probe = 0
    while probe < #group do
        probe = probe + 1
        pos = group[probe]

        for i,v in pairs(neighbor_dirs(pos)) do
            local newpos = pos + directions[v]
            local newhash = minetest.hash_node_position(newpos)

            if (not stones[newhash]) and (not checked[newhash]) then
                local newnode = check_position(newpos)

                local filter_result
                if early_termination_filter then
                    filter_result = early_termination_filter(newnode)
                end
                if filter_result then
                    filter_result.stones = stones
                    return filter_result
                elseif newnode == piece then
                    stones[newhash] = newpos
                    group[#group+1] = newpos
                else
                    checked[newhash] = true
                end
            end
        end
    end

    final_result = final_result()
    final_result.stones = stones
    return final_result
end

local function _check_captures_filter(node)
    if node:sub(1, 1) == "E" then
        return {capture = false}
    end
end

local function _check_captures_final()
    return {capture = true}
end

local function check_captures(pos)
    return connected_search(pos, _check_captures_final, _check_captures_filter)
end

local function _connected_group_final()
    return {}
end

local function connected_group(pos)
    return connected_search(pos, _connected_group_final)
end

local function territory_search(pos, max)
    if check_position(pos) ~= "E" then
        return {}
    end

    local team
    return connected_search(pos,
            function()
                return {team = team}
            end,
            function(node)
                if node == "E" then
                    max = max - 1
                    if max <= 0 then
                        return {}
                    end
                elseif node ~= "E_" and ((node:sub(1, 1) == "E") or (node:sub(1, 1) == "S")) and node:len() > 1 then
                    node = node:sub(2, -1)
                    if team then
                        if team ~= node then
                            return {}
                        end
                    else
                        team = node
                    end
                end
            end
    )
end

function lc_liberties.handle_placement(pos)
    cache = {}
    --minetest.chat_send_all(tostring(pos))
    --nodecore.node_sound(pos, "dug")

    local our_stone = check_position(pos)
    if our_stone:sub(1, 1) ~= "S" then
        return
    end
    our_stone = our_stone:sub(2, -1)

    local captureses = {}
    local captured = false
    for i,v in pairs(neighbor_dirs(pos)) do
        local new_pos = pos + directions[v]

        local hash = minetest.hash_node_position(new_pos)

        local checked = false
        for i2,v2 in pairs(captureses) do
            if v2.stones[hash] then
                checked = true
            end
        end

        if not checked then
            local node = check_position(new_pos)
            if (node:sub(1, 1) == "S") and (node:sub(2, -1) ~= our_stone) then
                local captures = check_captures(new_pos)
                captured = captured or captures.capture
                captureses[#captureses+1] = captures
            end
        end
    end

    if captured then
        for i,v in pairs(captureses) do
            if v.capture then
                local stone = minetest.get_node(v.stones[next(v.stones)]).name
                local count = 0

                local proximal
                local proximal_c = 0

                for i2, v2 in pairs(v.stones) do
                    local under = check_position(v2 + down)
                    if (under:sub(1, 1) == "W") and (under:len() > 1) then
                        nodecore.set_loud(v2, {name = "nc_fire:fire"})
                    else
                        nodecore.set_loud(v2, {name = "air"})
                    end
                    count = count + 1
                    if (v2:distance(pos) < 2.3) then
                        proximal_c = proximal_c + 1
                        if math.random(1, proximal_c) == 1 then
                            proximal = v2
                        end
                    end
                end

                local stack_max = minetest.registered_items[stone].stack_max
                while count > 0 do
                    nodecore.item_eject(proximal, stone .. " " .. math.min(count, stack_max), 3)
                    count = count - stack_max
                end
            end
        end
    else
        local captures = check_captures(pos)
        if captures.capture then
            local stone = minetest.get_node(pos).name
            nodecore.set_loud(pos, {name = "air"})
            nodecore.item_eject(pos, stone, 5)
        end
    end
end

function lc_liberties.handle_territory_fill(itemstack, placer, pointed_thing)
    cache = {}

    if (placer.get_player_control and placer:get_player_control().aux1)
            or
        (pointed_thing and pointed_thing.under and minetest.get_node(pointed_thing.under).name == "nc_items:stack")
            then
        return minetest.item_place(itemstack, placer, pointed_thing)
    end

    if pointed_thing and pointed_thing.above then
        local territories = territory_search(pointed_thing.above, itemstack:get_count())
        if territories.team then
            local piece = modname .. ":territory_" .. territories.team
            local count = 0
            for i, v in pairs(territories.stones) do
                nodecore.set_loud(v, {name = piece})
                count = count + 1
            end
            itemstack:set_count(itemstack:get_count() - count)
        end
    end

    return itemstack
end

function lc_liberties.handle_dig(pos, node, digger)
    cache = {}

    if (digger.get_player_control and digger:get_player_control().aux1)
                ~=
            (minetest.registered_items[node.name].groups.go_territory_marker ~= nil)
                then
        for i, v in pairs(connected_group(pos).stones) do
            minetest.node_dig(v, node, digger)
        end

        return true
    else
        return minetest.node_dig(pos, node, digger)
    end
end