--[[
    Liberally rewritten from:
    Camera, used under MIT license.
    Copyright 2018 angelickite

    Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
]]
local Event = require 'utils.event'
local mod_gui = require 'mod-gui'
local Command = require 'utils.command'
local Game = require 'utils.game'
local Gui = require 'utils.gui'
local Global = require 'utils.global'

local main_button_name = Gui.uid_name()

local camera_users = {}
Global.register(
    {
        camera_users = camera_users
    },
    function(tbl)
        camera_users = tbl.camera_users
    end
)

local zoomlevels = {1.00, 0.75, 0.50, 0.40, 0.30, 0.25, 0.20, 0.15, 0.10, 0.05}
local zoomlevellabels = {'100%', '75%', '50%', '40%', '30%', '25%', '20%', '15%', '10%', '5%'}
local sizelevels = {0, 100, 200, 250, 300, 350, 400, 450, 500}
local sizelevellabels = {'hide', '100x100', '200x200', '250x250', '300x300', '350x350', '400x400', '450x450', '500x500'}

local function apply_button_style(button)
    local button_style = button.style
    button_style.font = 'default-bold'
    button_style.height = 26
    button_style.top_padding = 0
    button_style.bottom_padding = 0
    button_style.left_padding = 2
    button_style.right_padding = 2
end

--- Takes args and a LuaPlayer and creates a camera GUI element
local function create_camera(args, player)
    local player_index = player.index
    local mainframeflow = mod_gui.get_frame_flow(player)
    local mainframeid = 'mainframe_' .. player_index
    local mainframe = mainframeflow[mainframeid]

    local target = game.players[args.target]
    if not target then
        player.print('Not a valid target')
        return
    end

    if not mainframe then
        mainframe = mainframeflow.add {type = 'frame', name = mainframeid, direction = 'vertical', style = 'captionless_frame'}
        mainframe.visible = true
    end

    local headerframe = mainframe.headerframe
    if not headerframe then
        mainframe.add {type = 'frame', name = 'headerframe', direction = 'horizontal', style = 'captionless_frame'}
    end

    local cameraframe = mainframe.cameraframe
    if not cameraframe then
        mainframe.add {type = 'frame', name = 'cameraframe', style = 'captionless_frame'}
    end

    mainframe.add {type = 'label', caption = 'Following: ' .. args.target}
    local close_button = mainframe.add {type = 'button', name = main_button_name, caption = 'Close'}
    apply_button_style(close_button)
    local target_index = target.index
    camera_users[player_index] = target_index
end

--- Takes table with a LuaPlayer under key player and destroys the camera of the associated player
local function destroy_camera(data)
    local player = data.player
    if not player then
        return
    end

    local player_index = player.index
    local mainframeflow = mod_gui.get_frame_flow(player)
    local mainframeid = 'mainframe_' .. player_index
    local mainframe = mainframeflow[mainframeid]

    if mainframe then
        mainframe.destroy()
        return true
    end
end

--- Destroys existing camera and, if applicable, creates a new one for the new target.
local function camera_command(args, player)
    destroy_camera({player = player})
    -- Once the old camera is destroyed, check to see if we need to make a new one
    if global.config.camera_disabled then
        player.print('The watch/camera function has been disabled for performance reasons.')
        return
    end
    if args and args.target and player then
        create_camera(args, player)
    end
end

local function update_camera_render(target, targetframe, zoom, size, visible)
    local position = {x = target.position.x, y = target.position.y - 0.5}
    local surface_index = target.surface.index
    local preview_size = size
    local camera = targetframe.camera

    if not camera then
        camera = targetframe.add {type = 'camera', name = 'camera', position = position, surface_index = surface_index, zoom = zoom}
    end

    camera.position = position
    camera.surface_index = surface_index
    camera.zoom = zoom
    camera.visible = visible
    camera.style.minimal_width = preview_size
    camera.style.minimal_height = preview_size
    camera.style.maximal_width = preview_size
    camera.style.maximal_height = preview_size
end

local function update_camera_zoom(targetframe)
    local zoomselection = targetframe.zoomselection
    local zoomlabels = {}

    for i = 1, #zoomlevellabels do
        zoomlabels[i] = {'', '' .. zoomlevellabels[i]}
    end
    if zoomselection then
        zoomselection.items = zoomlabels
    else
        zoomselection = targetframe.add {type = 'drop-down', name = 'zoomselection', items = zoomlabels, selected_index = 3}
    end

    local zoom = zoomlevels[zoomselection.selected_index]
    return zoom
end

local function update_camera_size(targetframe)
    local sizeselection = targetframe.sizeselection
    local sizelabels = {}

    for i = 1, #sizelevellabels do
        sizelabels[i] = {'', '' .. sizelevellabels[i]}
    end
    if sizeselection then
        sizeselection.items = sizelabels
    else
        sizeselection = targetframe.add {type = 'drop-down', name = 'sizeselection', items = sizelabels, selected_index = 4}
    end

    local size = sizelevels[sizeselection.selected_index]
    local visible = (size ~= 0)
    return size, visible
end

local function on_tick()
    if global.config.camera_disabled then
        return
    end
    for table_key, camera_table in pairs(camera_users) do
        local player = Game.get_player_by_index(table_key)
        local target = Game.get_player_by_index(camera_table)
        if not target.connected then
            destroy_camera({player = player})
            player.print('Target is offline, camera closed')
            camera_users[player.index] = nil
            return
        end
        local mainframeflow = mod_gui.get_frame_flow(player)
        local mainframeid = 'mainframe_' .. table_key
        local mainframe = mainframeflow[mainframeid]
        if mainframe then
            local headerframe = mainframe.headerframe
            local cameraframe = mainframe.cameraframe
            local zoom = update_camera_zoom(headerframe)
            local size, visible = update_camera_size(headerframe)
            update_camera_render(target, cameraframe, zoom, size, visible)
        end
    end
end

Command.add(
    'watch',
    {
        description = 'Allows you to watch other players.',
        arguments = {'target'},
        default_values = {target = false}
    },
    camera_command
)
Event.on_nth_tick(120, on_tick)
Gui.on_click(main_button_name, destroy_camera)