local BASE = (...):gsub('input', '')

local Widget = require(BASE..'widget')
local core = require(BASE..'core')

local utf8 = require 'utf8'

-- Grabs keyboard on focus
local Input = setmetatable({ grabkeyboard = true }, Widget)
Input.__index = Input


local function split(str, pos)
    local ofs = utf8.offset(str, pos) or 0
    return str:sub(1, ofs-1), str:sub(ofs)
end

function Input.new(args)
    local self = setmetatable(args, Input)

    self.text = self.text or ""
    self.color = self.color or core.theme.color
    self.cornerRadius = self.cornerRadius or core.theme.cornerRadius
    self.cursor = math.max(1, math.min(utf8.len(self.text)+1,
                                       self.cursor or utf8.len(self.text)+1))
    self.candidate = { text = "", start = 0, length = 0 }

    return self
end

function Input:onPointerInput(px,py, clicked)
    if clicked then
        self:grabFocus()

        -- Schedule cursor reposition for next draw()
        self.px = px
        self.py = py
    end
end

function Input:textedited(text, start, length)
    self.candidate.text = text
    self.candidate.start = start
    self.candidate.length = length
end

function Input:textinput(text)
    if text ~= "" then
        local a,b = split(self.text, self.cursor)

        self.text = table.concat {a, text, b}
        self.cursor = self.cursor + utf8.len(text)
    end
end

function Input:keypressed(key, code, isrepeat)
    if isrepeat == nil then
        -- LOVE sends 3 types of keypressed() events,
        -- 1. with isrepeat = true
        -- 2. with isrepeat = false
        -- 3. with isrepeat = nil
        --
        -- We're only interested in the first 2.
        return
    end

    if self.candidate.length == 0 then
        if key == 'backspace' then
            local a,b = split(self.text, self.cursor)

            self.text = table.concat { split(a, utf8.len(a)), b }
            self.cursor = math.max(1, self.cursor-1)

        elseif key == 'delete' then
            local a,b = split(self.text, self.cursor)
            local _,b = split(b, 2)

            self.text = table.concat { a, b }

        elseif key == 'left' then
            self.cursor = math.max(0, self.cursor-1)

        elseif key == 'right' then
            self.cursor = math.min(utf8.len(self.text)+1, self.cursor+1)
        end
    end
end

function Input:keyreleased(key)
    if self.candidate.length == 0 then
        if key == 'home' then
            self.cursor = 1
        elseif key == 'end' then
            self.cursor = utf8.len(self.text)+1
        elseif key == 'return' then
            self:onChange(self.text)
            self.cursor = 1
        end
    end
end

function Input:draw()
    -- Cursor position is before the char (including EOS) i.e. in "hello":
    --   position 1: |hello
    --   position 2: h|ello
    --   ...
    --   position 6: hello|

    local x,y,w,h = self.x,self.y,self.w,self.h
    local font = self.font or love.graphics.getFont()
    local th = font:getHeight()
    local tw = font:getWidth(self.text)

    -- Get size of text and cursor position
    local cursor_pos = 0
    if self.cursor > 1 then
        local s = self.text:sub(1, utf8.offset(self.text, self.cursor)-1)
        cursor_pos = font:getWidth(s)
    end

    -- Compute drawing offset
    if self.px ~= nil then
        -- Mouse movement
        local mx = self.px - self.x

        self.cursor = utf8.len(self.text) + 1
        for c = 1,self.cursor do
            local s = self.text:sub(0, utf8.offset(self.text, c)-1)
            if font:getWidth(s) >= mx then
                self.cursor = c-1
                break
            end
        end

        self.px,self.py = nil,nil
    end

    core.drawBox(x,y,w,h, self.color.normal, self.cornerRadius)

    -- Apply text margins
    w = math.max(w - 6, 0)
    x = math.min(x + 3, x + w)

    -- Set scissors
    local sx, sy, sw, sh = love.graphics.getScissor()
    love.graphics.setScissor(x-1,y,w+2,h)

    -- Text
    love.graphics.setColor(self.color.normal.fg)
    love.graphics.setFont(font)
    love.graphics.print(self.text, x, y + (h-th)/2)

    if self.candidate.length > 0 then
        -- Candidate text
        local ctw = font:getWidth(self.candidate.text)

        love.graphics.setColor(self.color.normal.fg)
        love.graphics.print(self.candidate.text, x + tw, y + (h-th)/2)

        -- Candidate text rectangle box
        love.graphics.rectangle('line', x + tw, y + (h-th)/2, ctw, th)

        self.candidate.text = ""
        self.candidate.start = 0
        self.candidate.length = 0
    end

    -- Cursor
    if self:isFocused() and (love.timer.getTime() % 1) > .5 then
        local ct = self.candidate
        local ss = ct.text:sub(1, utf8.offset(ct.text, ct.start))
        local ws = ct.start > 0 and font:getWidth(ss) or 0

        love.graphics.setLineWidth(1)
        love.graphics.setLineStyle('rough')
        love.graphics.line(x + cursor_pos + ws, y + (h-th)/2,
                           x + cursor_pos + ws, y + (h+th)/2)
    end

    -- Reset scissor
    love.graphics.setScissor(sx,sy,sw,sh)
end

return Input