//
// Copyright 2026 Aarav Ravindra Kharade
//

import CSystem
import CWayland

@_silgen_name("ark_wayland_client_init")
func c_ark_wayland_client_init() -> Bool

@_silgen_name("ark_wayland_client_shutdown")
func c_ark_wayland_client_shutdown()

@_silgen_name("ark_wayland_client_create_surface")
func c_ark_wayland_client_create_surface(_ width: Int32, _ height: Int32) -> UnsafeMutablePointer<UInt8>?

@_silgen_name("ark_wayland_client_commit")
func c_ark_wayland_client_commit()

/// ArkGraphics — Display Client Library
/// Connects to the ArkCompositor (Wayland Server) to render UI.
public class ArkGraphics {
    public var screenWidth: Int = 1920
    public var screenHeight: Int = 1080
    
    public var buffer: UnsafeMutablePointer<UInt8>?
    public private(set) var isConnected: Bool = false
    
    public init() {
        // For now, fallback to a standard 1080p resolution unless /tmp/screen_size.txt exists
        if let str = readFileContents("/tmp/screen_size.txt") {
            var w = 0
            var h = 0
            var parsingW = true
            for char in str {
                if char == " " {
                    parsingW = false
                } else if let num = char.wholeNumberValue {
                    if parsingW {
                        w = w * 10 + num
                    } else {
                        h = h * 10 + num
                    }
                }
            }
            if w > 0 && h > 0 {
                self.screenWidth = w
                self.screenHeight = h
            }
        }
        
        let maxRetries = 10
        for _ in 1...maxRetries {
            if c_ark_wayland_client_init() {
                isConnected = true
                break
            }
            usleep(500_000)
        }
        
        if isConnected {
            buffer = c_ark_wayland_client_create_surface(Int32(screenWidth), Int32(screenHeight))
            if buffer == nil {
                print("ArkGraphics: FATAL - Failed to create Wayland surface")
            }
        } else {
            print("ArkGraphics: WARNING - Failed to connect to Wayland server")
        }
    }
    
    deinit {
        if isConnected {
            c_ark_wayland_client_shutdown()
        }
    }
    
    @inline(__always)
    private func toTopLeftY(y: Int, h: Int) -> Int {
        return screenHeight - y - h
    }
    
    // - Rendering Commands -
    
    public func fillRectRGB(x: Int, y: Int, w: Int, h: Int, r: UInt8, g: UInt8, b: UInt8) {
        fillRectRGBA(x: x, y: y, w: w, h: h, r: r, g: g, b: b, a: 255)
    }
    
    public func fillRectRGBA(x: Int, y: Int, w: Int, h: Int, r: UInt8, g: UInt8, b: UInt8, a: UInt8) {
        guard let p = buffer else { return }
        let sy = toTopLeftY(y: y, h: h)
        
        let y0 = max(0, sy)
        let y1 = min(screenHeight, sy + h)
        let x0 = max(0, x)
        let x1 = min(screenWidth, x + w)
        
        for cy in y0..<y1 {
            let rowBase = cy * screenWidth * 4
            for cx in x0..<x1 {
                let off = rowBase + cx * 4
                if a == 255 {
                    p[off] = b
                    p[off+1] = g
                    p[off+2] = r
                    p[off+3] = 255
                } else {
                    let curA = Double(p[off+3]) / 255.0
                    let fVal = Double(a) / 255.0
                    let newA = curA + fVal * (1.0 - curA)
                    if newA > 0 {
                        p[off]   = UInt8(Double(b) * fVal + Double(p[off]) * curA * (1.0 - fVal))
                        p[off+1] = UInt8(Double(g) * fVal + Double(p[off+1]) * curA * (1.0 - fVal))
                        p[off+2] = UInt8(Double(r) * fVal + Double(p[off+2]) * curA * (1.0 - fVal))
                        p[off+3] = UInt8(newA * 255.0)
                    }
                }
            }
        }
    }
    
    public func fillRoundedRectRGB(x: Int, y: Int, w: Int, h: Int, r: UInt8, g: UInt8, b: UInt8, radius: Int) {
        fillRoundedRectRGBA(x: x, y: y, w: w, h: h, r: r, g: g, b: b, a: 255, radius: radius)
    }
    
    public func fillRoundedRectRGBA(x: Int, y: Int, w: Int, h: Int, r: UInt8, g: UInt8, b: UInt8, a: UInt8, radius: Int) {
        guard let p = buffer else { return }
        let sy = toTopLeftY(y: y, h: h)
        
        let y0 = max(0, sy)
        let y1 = min(screenHeight, sy + h)
        let x0 = max(0, x)
        let x1 = min(screenWidth, x + w)
        let radSq = Double(radius * radius)
        
        for cy in y0..<y1 {
            let rowBase = cy * screenWidth * 4
            for cx in x0..<x1 {
                var draw = true
                if radius > 0 {
                    // Check corners
                    let innerX0 = x + radius
                    let innerX1 = x + w - radius
                    let innerY0 = sy + radius
                    let innerY1 = sy + h - radius
                    
                    var dx = 0
                    var dy = 0
                    if cx < innerX0 { dx = innerX0 - cx }
                    else if cx > innerX1 { dx = cx - innerX1 }
                    if cy < innerY0 { dy = innerY0 - cy }
                    else if cy > innerY1 { dy = cy - innerY1 }
                    
                    if dx > 0 && dy > 0 {
                        if Double(dx*dx + dy*dy) > radSq {
                            draw = false
                        }
                    }
                }
                
                if draw {
                    let off = rowBase + cx * 4
                    p[off] = b
                    p[off+1] = g
                    p[off+2] = r
                    p[off+3] = a
                }
            }
        }
    }
    
    public func clear(r: UInt8, g: UInt8, b: UInt8) {
        guard let p = buffer else { return }
        let count = screenWidth * screenHeight * 4
        for i in stride(from: 0, to: count, by: 4) {
            p[i] = b
            p[i+1] = g
            p[i+2] = r
            p[i+3] = 255
        }
    }
    
    public func pan() {
        if isConnected {
            c_ark_wayland_client_commit()
        }
    }
    
    public func drawHLine(x: Int, y: Int, w: Int, r: UInt8, g: UInt8, b: UInt8) {
        fillRectRGB(x: x, y: y, w: w, h: 1, r: r, g: g, b: b)
    }
    
    public func drawVLine(x: Int, y: Int, h: Int, r: UInt8, g: UInt8, b: UInt8) {
        fillRectRGB(x: x, y: y, w: 1, h: h, r: r, g: g, b: b)
    }
    
    public func drawRectOutline(x: Int, y: Int, w: Int, h: Int, r: UInt8, g: UInt8, b: UInt8, thickness: Int = 1) {
        fillRectRGB(x: x, y: y, w: w, h: thickness, r: r, g: g, b: b)
        fillRectRGB(x: x, y: y + h - thickness, w: w, h: thickness, r: r, g: g, b: b)
        fillRectRGB(x: x, y: y, w: thickness, h: h, r: r, g: g, b: b)
        fillRectRGB(x: x + w - thickness, y: y, w: thickness, h: h, r: r, g: g, b: b)
    }
}