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local json = require"common.dkjson"
local class = require"common.class"
local coords = require"common.coords"
local rle = require"common.rle"
local CHUNK_SIZE = require"common.constants".CHUNK_SIZE
local function index_ok(offq,offr)
return 0<=offq and 0<=offr and offq<CHUNK_SIZE and offr<CHUNK_SIZE
end
local function index(offq,offr)
-- indexes start at 0
-- and go up to (CHUNK_SIZE^2)-1
assert(index_ok(offq,offr), "chunk hex offset out of bounds")
return CHUNK_SIZE*offq + offr + 1
end
local Chunk = class()
function Chunk.make(cls,cp,tiles)
return setmetatable({cp=cp,tiles=tiles},cls)
end
function Chunk.at(self,hoffs)
-- errors if invalid offset
return self:_atqr(hoffs.q,hoffs.r)
end
function Chunk._atqr(self,q,r)
return self.tiles[index(q,r)]
end
function Chunk.set_at(self,hoffs,tile)
-- errors if invalid offset
self.tiles[index(hoffs.q,hoffs.r)] = tile
end
function Chunk.data_packet(self)
return json.encode{
t="chunk", tiles=rle.encode(self.tiles),
u=self.cp.u, v=self.cp.v
}
end
function Chunk.from_packet_data(cls,packet)
-- assuming packet has already been json.decoded
-- since otherwise how would we know it's a chunk packet
local cp = coords.ChunkPos:make(packet.u,packet.v)
return cls:make(cp,rle.decode(packet.tiles))
end
return {
Chunk=Chunk,
index=index,
index_ok=index_ok,
}
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