local expect = require("cc.expect").expect
local function todo() error("todo!") end
local pretty = require "cc.pretty"

local BigTerm = {
    write = function(self, text)
        local w = self.getSize()
        for i = 1, #text do
            if self._pos.x <= w then
                self._blitpixel(
                    self._pos.x,
                    self._pos.y,
                    text:sub(i, i),
                    self._colorChar(self._colorForeground),
                    self._colorChar(self._colorBackground)
                    )
                self._pos.x = self._pos.x + 1
            end
        end
    end,
    blit = function(self, text, foreground, background)
        local x, y = self._pos.x, self._pos.y
        local w = #text
        local LIMIT = 0
        local ox = 1
        while w > 0 and LIMIT < 20 do
            local mon, i, lx, ly = self._getMonitorForScreenPos(x, y)
            if not mon then break end
            local remaining = mon._w - lx
            mon.p.setCursorPos(lx + 1, ly + 1)
            mon.p.blit(
                text:sub(ox, ox + w),
                foreground:sub(ox, ox + w - 1),
                background:sub(ox, ox + w - 1)
            )
            w = w - remaining
            x = x + remaining
            ox = ox + remaining
        end
    end,
    clear = function(self)
        self._forEachMonitor(function(mon)
            mon.p.clear()
        end)
    end,
    clearLine = function(self) todo() end,
    scroll = function(self, n)
        -- TODO: NOPE! store framebuffer and write lines onto other screens
        self._forEachMonitor(function(mon)
            mon.p.scroll(n)
        end)
    end,

    getCursorPos = function(self) return self._pos.x, self._pos.y end,
    setCursorPos = function(self, x, y)
        self._pos.x = x
        self._pos.y = y
        -- TODO: move cursor to the correct monitor and hide it from others
    end,

    setCursorBlink = function(self, state) todo() end,
    getCursorBlink = function(self) todo() end,

    isColor = function(self) return true end,
    getSize = function(self)
        local w, h = 0, 0
        for ix = 1, self._w do
            local mon = self._findMonitor(ix, 1)
            w = w + mon._w
        end
        for iy = 1, self._h do
            local mon = self._findMonitor(1, iy)
            h = h + mon._h
        end
        return w, h
    end,

    setTextColor = function(self, fg)
        self._forEachMonitor(function(mon)
            mon.p.setTextColor(fg)
        end)
        self._colorForeground = fg
    end,
    getTextColor = function(self) todo() end,

    setBackgroundColor = function(self, bg)
        self._forEachMonitor(function(mon)
            mon.p.setBackgroundColor(bg)
        end)
        self._colorBackground = bg
    end,
    getBackgroundColor = function(self) todo() end,

    setTextScale = function(self, scale)
        self._scale = scale
        self._reset()
    end,
    getTextScale = function(self)
        return self._scale
    end,

    setPaletteColor = function(self, index, color, g, b)
        expect(1, index, "number")
        expect(2, color, "number")
        expect(3, g, "number", "nil")
        expect(4, b, "number", "nil")
        if index < 0 or index > 32768 or math.log(index, 2) % 1 ~= 0 then
            error("index out of range")
        end

        local r = color
        if g == nil or b == nil then
            if color < 0 or color > 0xFFFFFF then
                error("color out of range")
            end
            r = bit.band(0xFF, bit.brshift(color, 16)) / 255
            g = bit.band(0xFF, bit.brshift(color, 8)) / 255
            b = bit.band(0xFF, bit.brshift(color, 0)) / 255
        else
            if r < 0 or r > 1.0 then error("red channel out of range") end
            if g < 0 or g > 1.0 then error("green channel out of range") end
            if b < 0 or b > 1.0 then error("blue channel out of range") end
        end

        self._palette[index] = bit.bor(
            bit.blshift(math.floor(r * 255), 16),
            bit.blshift(math.floor(g * 255), 8),
            bit.blshift(math.floor(b * 255), 0)
        )
        self._forEachMonitor(function(mon)
            mon.p.setPaletteColor(index, r, g, b)
        end)
    end,
    getPaletteColor = function(self, index) todo() end,

    -- internals

    _colorChar = function(self, v)
        return string.format("%x", math.floor(math.log(v, 2)))
    end,

    _reset = function(self)
        self._w = 1
        self._h = 1
        self._forEachMonitor(function(mon, i)
            mon.p.setTextScale(self._scale)
            local w, h = mon.p.getSize()
            self._monitors[i]._w = w
            self._monitors[i]._h = h
            if mon.x > self._w then self._w = mon.x end
            if mon.y > self._h then self._h = mon.y end
            for id, color in pairs(self._palette) do
                mon.p.setPaletteColor(id, color)
            end
        end)
    end,

    _blitpixel = function(self, x, y, c, bg, fg)
        bg = bg or "0"
        fg = fg or "f"
        local mon = self._getMonitorForScreenPos(x, y)
        mon.p.setCursorPos(((x - 1) % mon._w) + 1, ((y - 1) % mon._h) + 1)
        mon.p.blit(c, bg, fg)
    end,

    _findMonitor = function(self, x, y)
        for i = 1, #self._monitors do
            local mon = self._monitors[i]
            if mon.x == x and mon.y == y then
                return mon, i
            end
        end
    end,

    _getMonitorForScreenPos = function(self, x, y)
        local oy = 1
        for iy = 1, self._h do
            local ox = 1
            for ix = 1, self._w do
                local mon, i = self._findMonitor(ix, iy)
                if x >= ox and x < (ox + mon._w) and y >= oy and y < (oy + mon._h) then
                    return mon, i, x - ox, y - oy
                end
                ox = ox + mon._w
            end
            local mon, i = self._findMonitor(1, iy)
            oy = oy + mon._h
        end
    end,

    _forEachMonitor = function(self, fun)
        for i = 1, #self._monitors do
            fun(self._monitors[i], i)
        end
    end,

}

return function(monitors, args)
    args = args or {}
    local mon = setmetatable({
        _monitors = monitors,
        _pos = { x = 1, y = 1 },
        _blink = false,
        _colorForeground = colors.white,
        _colorBackground = colors.black,
        _scale = args.scale or 1.0,
        _palette = args.palette or {},
    }, { __index = BigTerm })
    for name, method in pairs(BigTerm) do
        if type(method) == "function" then
            mon[name] = function(...) return method(mon, ...) end
        end
    end
    mon._reset()
    return mon
end