local World = require("game.world")

local Camera = {
    x = 2000,
    y = 900,
    zoom = 0.35,
}

local MAX_ZOOM = 3.5
local MIN_ZOOM = 0.3
local ZOOM_SPEED = 2.0

function Camera.update(lander, terrain, dt)
    -- Track lander X
    Camera.x = lander.x

    -- Get ground height below lander
    local groundY = terrain.getHeightAt(lander.x)
    local altitude = groundY - lander.y

    -- Camera Y: keep terrain in the lower portion of the viewport even at high altitude
    local targetY = lander.y + altitude * 0.45

    Camera.y = Camera.y + (targetY - Camera.y) * math.min(1, dt * 3)

    -- Zoom: fit the distance from lander to ground within the viewport
    -- We want the full altitude span to fit in about 70% of screen height
    local sw, sh = World.screenW, World.screenH
    local effectiveScale = World.baseScale
    local neededHeight = math.max(altitude + 100, 200)  -- minimum view range
    local viewportFraction = 0.7
    local targetZoom = (sh * viewportFraction) / (neededHeight * effectiveScale)
    targetZoom = math.max(MIN_ZOOM, math.min(MAX_ZOOM, targetZoom))

    Camera.zoom = Camera.zoom + (targetZoom - Camera.zoom) * math.min(1, dt * ZOOM_SPEED)
end

function Camera.getAltitude(landerY, terrain, landerX)
    local groundY = terrain.getHeightAt(landerX)
    return math.max(0, groundY - landerY)
end

function Camera.applyTransform()
    local sw, sh = World.screenW, World.screenH
    local scale = World.baseScale * Camera.zoom

    love.graphics.push()
    love.graphics.translate(sw / 2, sh / 2)
    love.graphics.scale(scale)
    love.graphics.translate(-Camera.x, -Camera.y)
end

function Camera.popTransform()
    love.graphics.pop()
end

function Camera.getVisibleRect()
    local sw, sh = World.screenW, World.screenH
    local scale = World.baseScale * Camera.zoom
    local hw = (sw / 2) / scale
    local hh = (sh / 2) / scale
    return Camera.x - hw, Camera.y - hh, Camera.x + hw, Camera.y + hh
end

function Camera.getZoom()
    return Camera.zoom
end

function Camera.reset()
    Camera.x = 2000
    Camera.y = 900
    Camera.zoom = MIN_ZOOM
end

return Camera