use std::path::{Path,PathBuf};
use std::fs;
use {Config,Result,ImageHeader,MetaInfo,PathExt};

#[derive(Clone)]
pub struct Partition {
    path: PathBuf,
    hinfo: Option<HeaderInfo>,
    is_mounted: bool,
}

#[derive(Clone)]
struct HeaderInfo {
    header: ImageHeader,
    metainfo: MetaInfo,
}

impl Partition {
    pub fn rootfs_partitions(config: &Config) -> Result<Vec<Partition>> {
        let mut v = Vec::new();
        for path in rootfs_partition_paths()? {
            let partition = Partition::load(&path, config)?;
            v.push(partition);
        }
        Ok(v)
    }

    fn load(dev: &Path, config: &Config) -> Result<Partition> {
        let is_mounted = is_path_mounted(dev)?;
        let header = Partition::load_header(dev, config)?;
        Ok(Partition::new(dev, header, is_mounted))
    }

    fn load_header(dev: &Path, config: &Config) -> Result<Option<HeaderInfo>> {
        let header = ImageHeader::from_partition(dev)?;
        if !header.is_magic_valid() {
            return Ok(None);
        }
        let metainfo = match header.verified_metainfo(config) {
            Ok(metainfo) => metainfo,
            Err(e) => {
                warn!("Reading partition {}: {}", dev.display(), e);
                return Ok(None);
            },
        };
        Ok(Some(HeaderInfo {
            header, metainfo
        }))
    }

    fn new(path: &Path, hinfo: Option<HeaderInfo>, is_mounted: bool) -> Partition {
        Partition {
            path: path.to_owned(), 
            hinfo, is_mounted,
        }
    }

    pub fn path(&self) -> &Path {
        &self.path
    }

    pub fn is_mounted(&self) -> bool {
        self.is_mounted
    }

    pub fn is_initialized(&self) -> bool {
        self.hinfo.is_some()
    }

    pub fn header(&self) -> &ImageHeader {
        assert!(self.is_initialized());
        &self.hinfo.as_ref().unwrap().header
    }

    fn header_mut(&mut self) -> &mut ImageHeader {
        assert!(self.is_initialized());
        &mut self.hinfo.as_mut().unwrap().header
    }

    pub fn metainfo(&self) -> &MetaInfo {
        assert!(self.is_initialized());
        &self.hinfo.as_ref().unwrap().metainfo
    }

    pub fn is_new(&self) -> bool {
        self.header().status() == ImageHeader::STATUS_NEW
    }

    pub fn is_good(&self) -> bool {
        self.header().status() == ImageHeader::STATUS_GOOD
    }

    pub fn is_preferred(&self) -> bool {
        self.header().has_flag(ImageHeader::FLAG_PREFER_BOOT)
    }

    pub fn write_status(&mut self, status: u8) -> Result<()> {
        self.header_mut().set_status(status);
        self.header().write_partition(&self.path)
    }

    /// Called at boot to perform various checks and possibly
    /// update the status field to an error state.
    ///
    /// Mark `STATUS_TRY_BOOT` partition as `STATUS_FAILED`.
    ///
    /// If metainfo cannot be parsed, mark as `STATUS_BAD_META`.
    ///
    /// Verify metainfo signature and mark `STATUS_BAD_SIG` if
    /// signature verification fails.
    ///
    pub fn boot_scan(&mut self, config: &Config) -> Result<()> {
        if !self.is_initialized() {
            return Ok(())
        }
        if self.header().status() == ImageHeader::STATUS_TRY_BOOT {
            self.write_status(ImageHeader::STATUS_FAILED)?;
        }
        // XXX verify signature
        Ok(())
    }
}

fn rootfs_partition_paths() -> Result<Vec<PathBuf>> {
    let mut rootfs_paths = Vec::new();
    for dent in fs::read_dir("/dev/mapper")? {
        let path = dent?.path();
        if is_path_rootfs(&path) {
            rootfs_paths.push(path);
        }
    }
    Ok(rootfs_paths)
}

fn is_path_rootfs(path: &Path) -> bool {
    path_filename(path).starts_with("citadel-rootfs")
}

fn path_filename(path: &Path) -> &str {
    if let Some(osstr) = path.file_name() {
        if let Some(name) = osstr.to_str() {
            return name;
        }
    }
    ""
}

///
/// Returns `true` if `path` matches the source field (first field) 
/// of any of the mount lines listed in /proc/mounts
///
pub fn is_path_mounted(path: &Path) -> Result<bool> {
    let path_str = path.to_str().unwrap();

    for line in Path::new("/proc/mounts").read_as_lines()? {
        if let Some(s) = line.split_whitespace().next() {
            if s == path_str {
                return Ok(true);
            }
        }
    }
    Ok(false)
}