use std::process::Command;
use std::env;
use std::fs;
use std::path::Path;

fn main() {
    // 检测当前是否在树莓派上
    let is_raspberry_pi = detect_raspberry_pi();
    
    // 自动启用GPIO功能（仅当是树莓派时）
    if is_raspberry_pi {
        println!("cargo:rustc-cfg=feature=\"gpio\"");
        println!("cargo:warning=Raspberry Pi detected, enabling gpio feature");
    } else {
        println!("cargo:warning=Not running on Raspberry Pi, gpio feature NOT enabled");
    }
    
    // 通过包含的 OpenCV 库检测版本
    let opencv_version = detect_opencv_version();
    
    println!("cargo:rustc-env=OPENCV_VERSION={}", opencv_version);
    
    // 解析版本
    let version_parts: Vec<&str> = opencv_version.split('.').collect();
    let major = version_parts.get(0).and_then(|s| s.parse::<u32>().ok()).unwrap_or(0);
    let minor = version_parts.get(1).and_then(|s| s.parse::<u32>().ok()).unwrap_or(0);
    
    // 如果版本 >= 4.11.0，启用特性
    if major > 4 || (major == 4 && minor >= 11) {
        println!("cargo:rustc-cfg=feature=\"opencv-4-11-plus\"");
        println!("cargo:warning=Detected OpenCV {} >= 4.11.0, enabling opencv-4-11-plus feature", opencv_version);
    } else {
        println!("cargo:warning=Detected OpenCV {}, opencv-4-11-plus feature NOT enabled", opencv_version);
    }
}

fn detect_raspberry_pi() -> bool {
    // 方法1: 检查是否是Linux系统（必要条件）
    let is_linux = env::consts::OS == "linux";
    if !is_linux {
        return false;
    }
    
    // 方法2: 检查/proc/cpuinfo是否包含Raspberry Pi的特征
    if let Ok(cpuinfo) = fs::read_to_string("/proc/cpuinfo") {
        if cpuinfo.contains("Raspberry Pi") || 
           cpuinfo.contains("BCM2708") || 
           cpuinfo.contains("BCM2709") || 
           cpuinfo.contains("BCM2710") || 
           cpuinfo.contains("BCM2711") ||
           cpuinfo.contains("BCM2835") || 
           cpuinfo.contains("BCM2836") || 
           cpuinfo.contains("BCM2837") ||
           cpuinfo.contains("BCM2838") {
            return true;
        }
    }
    
    // 方法3: 检查树莓派特有的设备树模型文件
    if let Ok(model) = fs::read_to_string("/sys/firmware/devicetree/base/model") {
        if model.contains("Raspberry Pi") {
            return true;
        }
    }
    
    // 方法4: 检查是否存在树莓派特有的库
    let lib_check = Command::new("ldconfig")
        .args(["-p"])
        .output()
        .ok()
        .and_then(|output| {
            if output.status.success() {
                let libraries = String::from_utf8_lossy(&output.stdout);
                if libraries.contains("librpgpio") || libraries.contains("libraspberrypi") {
                    Some(true)
                } else {
                    None
                }
            } else {
                None
            }
        });
    
    if lib_check.is_some() {
        return true;
    }
    
    // 方法5: 检查树莓派特有的配置文件
    if Path::new("/boot/config.txt").exists() || Path::new("/boot/firmware/config.txt").exists() {
        // 这个文件在大多数树莓派系统上存在
        return true;
    }
    
    // 检查是否在CARGO_FEATURE_GPIO环境变量中强制启用
    // 这允许用户手动启用GPIO功能（覆盖自动检测）
    if env::var("CARGO_FEATURE_GPIO").is_ok() {
        return true;
    }
    
    // 否则默认为false
    false
}

fn detect_opencv_version() -> String {
    // 方法 1: 尝试使用 pkg-config
    if let Some(version) = try_pkg_config() {
        return version;
    }
    
    // 方法 2: 尝试使用 opencv_version 命令
    if let Some(version) = try_opencv_version_command() {
        return version;
    }
    
    // 方法 3: 尝试编译并运行一个小程序来检测版本
    if let Some(version) = try_compile_check() {
        return version;
    }
    
    // 方法 4: 检查 OpenCV 头文件
    if let Some(version) = try_header_check() {
        return version;
    }
    
    // 回退到默认版本
    let default_version = "4.0.0".to_string();
    println!("cargo:warning=Could not detect OpenCV version, assuming {}", default_version);
    default_version
}

fn try_pkg_config() -> Option<String> {
    // 尝试使用 pkg-config 来获取 OpenCV 版本
    let output = Command::new("pkg-config")
        .args(["--modversion", "opencv4"])
        .output()
        .ok()?;
    
    if output.status.success() {
        let version = String::from_utf8(output.stdout).ok()?;
        let version = version.trim().to_string();
        if !version.is_empty() {
            return Some(version);
        }
    }
    
    // 尝试 opencv 包（旧版本）
    let output = Command::new("pkg-config")
        .args(["--modversion", "opencv"])
        .output()
        .ok()?;
    
    if output.status.success() {
        let version = String::from_utf8(output.stdout).ok()?;
        let version = version.trim().to_string();
        if !version.is_empty() {
            return Some(version);
        }
    }
    
    None
}

fn try_opencv_version_command() -> Option<String> {
    // 尝试运行 opencv_version 命令
    let output = Command::new("opencv_version")
        .output()
        .ok()?;
    
    if output.status.success() {
        let version = String::from_utf8(output.stdout).ok()?;
        let version = version.trim().to_string();
        if !version.is_empty() {
            return Some(version);
        }
    }
    
    None
}

fn try_compile_check() -> Option<String> {
    // 创建一个临时目录
    let out_dir = env::var("OUT_DIR").ok()?;
    let temp_file = format!("{}/version_check.cpp", out_dir);
    let temp_exe = format!("{}/version_check", out_dir);
    
    // 写入一个简单的 C++ 程序来打印 OpenCV 版本
    std::fs::write(&temp_file, r#"
        #include <opencv2/core.hpp>
        #include <iostream>
        
        int main() {
            std::cout << CV_VERSION << std::endl;
            return 0;
        }
    "#).ok()?;
    
    // 尝试编译
    let status = Command::new("c++")
        .args([&temp_file, "-o", &temp_exe, "-lopencv_core"])
        .status()
        .ok()?;
    
    if !status.success() {
        return None;
    }
    
    // 运行程序获取版本
    let output = Command::new(&temp_exe)
        .output()
        .ok()?;
    
    if output.status.success() {
        let version = String::from_utf8(output.stdout).ok()?;
        let version = version.trim().to_string();
        if !version.is_empty() {
            return Some(version);
        }
    }
    
    None
}

fn try_header_check() -> Option<String> {
    // 尝试在常见位置查找 OpenCV 头文件
    let paths = [
        "/usr/include/opencv4/opencv2/core/version.hpp",
        "/usr/local/include/opencv4/opencv2/core/version.hpp",
        "/usr/include/opencv2/core/version.hpp",
        "/usr/local/include/opencv2/core/version.hpp",
        "/opt/homebrew/include/opencv4/opencv2/core/version.hpp",
        "/opt/homebrew/include/opencv2/core/version.hpp",
    ];
    
    for path in paths.iter() {
        if let Ok(content) = std::fs::read_to_string(path) {
            // 查找版本定义 #define CV_VERSION_MAJOR 4
            let mut major = None;
            let mut minor = None;
            let mut patch = None;
            
            for line in content.lines() {
                if let Some(value) = extract_define(line, "CV_VERSION_MAJOR") {
                    major = Some(value);
                } else if let Some(value) = extract_define(line, "CV_VERSION_MINOR") {
                    minor = Some(value);
                } else if let Some(value) = extract_define(line, "CV_VERSION_REVISION") {
                    patch = Some(value);
                }
                
                if major.is_some() && minor.is_some() && patch.is_some() {
                    return Some(format!("{}.{}.{}", major.unwrap(), minor.unwrap(), patch.unwrap()));
                }
            }
        }
    }
    
    None
}

fn extract_define(line: &str, define_name: &str) -> Option<String> {
    let line = line.trim();
    if line.starts_with("#define") && line.contains(define_name) {
        let parts: Vec<&str> = line.split_whitespace().collect();
        if parts.len() >= 3 && parts[1] == define_name {
            return Some(parts[2].to_string());
        }
    }
    None
}