Freecam

local function getEyeAngles( ply )
    return ply:InVehicle()
        and select( 2, ply:GetVehicle():GetVehicleViewPosition() )
         or ply:EyeAngles()
end

local function isDown( cmd, key )
    local isDown = cmd:KeyDown( key )

    if isDown then
        cmd:RemoveKey( key )
    end

    return isDown
end

if FreeCam then
    if FreeCam.enabled then
        FreeCam:Toggle()

        if IsValid( FreeCam.panel ) then
            FreeCam.panel:Remove()
        end
    end
end

FreeCam = {
    enabled = FreeCam and FreeCam.enabled or false,
    movementEnabled = FreeCam and FreeCam.movementEnabled or false,
    followingEnabled = FreeCam and FreeCam.followingEnabled or false,
    pos = FreeCam and FreeCam.pos or nil,
    ang = FreeCam and FreeCam.ang or nil,
    speed = FreeCam and FreeCam.speed or 10,
    physicalAngles = FreeCam and FreeCam.physicalAngles or Angle(),
    m_yaw = 0,
    m_pitch = 0,
    panel = NULL,
}

local function updateSensivity()
    FreeCam.m_yaw = tonumber( GetConVar( 'm_yaw' ):GetString() ) or FreeCam.m_yaw
    FreeCam.m_pitch = tonumber( GetConVar( 'm_pitch' ):GetString() ) or FreeCam.m_pitch
end

updateSensivity()
timer.Create( 'UpdateThirdPersonViewSensivity', 10, 0, updateSensivity )

function FreeCam:Toggle()
    self.enabled = !self.enabled

    if self.enabled then
        if !self.pos or !self.ang then
            self:Reset()
        end

        self:ShowGUI()

        hook.Add( 'CalcView', 'FreeCam', function( ... )
            return self:CalcView( ... )
        end )
    else
        self:HideGUI()
        hook.Remove( 'CalcView', 'FreeCam' )
    end

    if !self.movementEnabled then
        self.physicalAngles = LocalPlayer():EyeAngles()
    end

    return self.enabled
end

function FreeCam:ToggleMovement()
    self.movementEnabled = !self.movementEnabled

    if !self.movementEnabled then
        self.physicalAngles = LocalPlayer():EyeAngles()
    end

    return self.movementEnabled
end

function FreeCam:ToggleFollowing()
    self.followingEnabled = !self.followingEnabled

    if self.pos then
        if self.followingEnabled then
            self.pos = self.pos - LocalPlayer():GetPos()
        else
            self.pos = self.pos + LocalPlayer():GetPos()
        end
    end

    return self.followingEnabled
end

function FreeCam:ToggleGUI()
    if IsValid( self.panel ) then
        self:HideGUI()
    else
        self:ShowGUI()
    end
end

function FreeCam:Reset()
    self.pos = LocalPlayer():GetShootPos()

    if self.followingEnabled then
        self.pos = self.pos - LocalPlayer():GetPos()
    end

    self.ang = getEyeAngles( LocalPlayer() )
end

function FreeCam:Init()
    hook.Add( 'HUDPaint', 'FreeCam', function( ... )
        return self:HUDPaint( ... )
    end )

    hook.Add( 'HUDShouldDraw', 'FreeCam', function( ... )
        return self:HUDShouldDraw( ... )
    end )

    hook.Add( 'StartCommand', 'FreeCam', function( ... )
        return self:StartCommand( ... )
    end )

    concommand.Add( 'aoki_freecam_toggle', function()
        local enabled = self:Toggle()
        print( '[Freecam] Freecam ' .. ( enabled and 'enabled' or 'disabled' ) )
    end )

    concommand.Add( 'aoki_freecam_toggle_movement', function()
        local enabled = self:ToggleMovement()
        print( '[Freecam] Movement ' .. ( enabled and 'enabled' or 'disabled' ) )
    end )

    concommand.Add( 'aoki_freecam_toggle_following', function()
        local enabled = self:ToggleFollowing()
        print( '[Freecam] Following ' .. ( enabled and 'enabled' or 'disabled' ) )
    end )

    concommand.Add( 'aoki_freecam_reset_camera', function()
        self:Reset()
        print( '[Freecam] Camera reset' )
    end )

    concommand.Add( 'aoki_freecam_destroy', function()
        self:Destroy()
        print( '[Freecam] FreeCam destroyed' )
    end )
end

function FreeCam:Destroy()
    hook.Remove( 'CalcView', 'FreeCam' )
    hook.Remove( 'StartCommand', 'FreeCam' )
end

function FreeCam:ShowGUI()
    if IsValid( self.panel ) then return end

    local panel = vgui.Create( 'DPanel' )
    self.panel = panel
    panel.freecam = self
    panel:SetSize( 1, 1 )
    panel:SetRenderInScreenshots( false )
    panel:SetPaintedManually( true )
    panel:NoClipping( true )

    local font = 'Trebuchet24'

    function panel:Paint()
        if !self.freecam.enabled then
            return
        end

        local text = string.format(
            '[Freecam enabled]\nControlling: %s\nSpeed: %s',
            self.freecam.movementEnabled and 'Player' or 'Camera',
            self.freecam.speed
        )

        local x, y = ScrW() / 2, 5

        draw.DrawText( text, font, x + 1, y + 1, Color( 50, 50, 50 ), TEXT_ALIGN_CENTER )
        draw.DrawText( text, font, x, y, Color( 255, 255, 255 ), TEXT_ALIGN_CENTER )

        render.DrawLine( LocalPlayer():GetShootPos(), LocalPlayer():GetEyeTrace().HitPos, color_white )
    end
end

function FreeCam:HideGUI()
    if IsValid( self.panel ) then
        self.panel:Remove()
    end
end

function FreeCam:HUDPaint()
    if IsValid( self.panel ) then
        self.panel:PaintManual( true )
    end
end

function FreeCam:CalcView( ply, pos, ang, fov )
    if !self.enabled then
        return
    end

    local pos = self.pos
    local ang = self.ang

    if self.followingEnabled then
        pos = LocalPlayer():GetPos()
        pos:Add( self.pos )
    end

    local view = {
        origin = pos,
        angles = ang,
        fov = fov,
        drawviewer = true,
    }

    return view
end

function FreeCam:HUDShouldDraw( name )
    if name == 'CHudWeaponSelection' and self.enabled and !self.movementEnabled then
        return false
    end
end

function FreeCam:StartCommand( _, cmd )
    if !self.enabled or self.movementEnabled then
        return
    end

    local wheel = cmd:GetMouseWheel()

    if wheel != 0 then
        self.speed = math.Clamp( self.speed + wheel * math.abs( wheel ), 1, 100 )
    end

    local w = isDown( cmd, IN_FORWARD ) and 1 or 0
    local s = isDown( cmd, IN_BACK ) and 1 or 0
    local a = isDown( cmd, IN_MOVELEFT ) and 1 or 0
    local d = isDown( cmd, IN_MOVERIGHT ) and 1 or 0
    local space = isDown( cmd, IN_JUMP ) and 1 or 0
    local ctrl = isDown( cmd, IN_DUCK ) and 1 or 0
    local shift = isDown( cmd, IN_SPEED )
    local r = isDown( cmd, IN_RELOAD )

    if r and shift then
        self:Reset()
    end

    local coefficient = FrameTime() * self.speed * self.speed * ( shift and 2 or 1 )

    self.pos:Add( ( w - s ) * self.ang:Forward() * coefficient )
    self.pos:Add( ( d - a ) * self.ang:Right() * coefficient )

    --- Moves the camera by Z axis relatively to the camera angles ---
    --self.pos:Add( ( space - ctrl ) * self.ang:Up() * coefficient )

    --- Moves the camera by Z axis relatively to the world ---
    self.pos.z = self.pos.z + ( space - ctrl ) * coefficient

    local mouseX = cmd:GetMouseX()
    local mouseY = cmd:GetMouseY()

    self.ang.pitch = self.ang.pitch + mouseY * FreeCam.m_pitch
    self.ang.yaw = self.ang.yaw + mouseX * -FreeCam.m_yaw

    cmd:ClearMovement()
    cmd:ClearButtons()
    cmd:SetViewAngles( self.physicalAngles )
    cmd:SetMouseWheel( 0 )
end

FreeCam:Init()