use std::path::PathBuf;

use elf_utilities::{
    file::{ELF64Dumper, ELF64},
    section::Section64,
    segment::{Segment64, Type},
};

use crate::{
    common::{Output, Section, SectionInfo},
    error::Error,
};

use super::ElfObject;

pub struct ElfOutput<'data> {
    destination: PathBuf,
    dump: ELF64Dumper,
    text: Vec<SectionInfo<'data>>,
    data: Vec<SectionInfo<'data>>,
    bss: Vec<SectionInfo<'data>>,
}

impl ElfOutput<'_> {
    pub fn new(destination: PathBuf) -> Self {
        use elf_utilities::header::{Class, Data, Machine, Type, Version, OSABI};

        let mut elf = ELF64::default();
        elf.ehdr.set_elf_type(Type::Exec);
        elf.ehdr.set_class(Class::Bit64);
        elf.ehdr.set_machine(Machine::Intel386);
        elf.ehdr.set_object_version(Version::Current);
        elf.ehdr.set_file_version(Version::Current);
        elf.ehdr.set_osabi(OSABI::Linux);
        elf.ehdr.set_data(Data::LSB2);

        Self {
            destination,
            dump: ELF64Dumper::new(elf),
            text: Vec::new(),
            data: Vec::new(),
            bss: Vec::new(),
        }
    }

    pub fn from_object(object: &ElfObject, destination: PathBuf) -> Self {
        use elf_utilities::header::Type;

        let other = object.elf();

        let mut elf = ELF64::default();
        elf.ehdr = other.ehdr.clone();
        elf.ehdr.set_elf_type(Type::Exec);

        Self {
            destination,
            dump: ELF64Dumper::new(elf),
            text: Vec::new(),
            data: Vec::new(),
            bss: Vec::new(),
        }
    }

    fn populate_section_data(&mut self) -> Result<u64, Error> {
        use elf_utilities::section::{Contents64, Shdr64, Type};

        let mut data = Vec::new();

        for t in self.text.iter_mut() {
            if let Some(iter) = &mut t.data {
                data.extend(iter.as_mut());
            }
        }

        let mut header = Shdr64::default();
        header.set_type(Type::ProgBits);
        header.sh_entsize = data.len() as u64;

        let sec64 = Section64 {
            name: ".text".into(),
            header,
            contents: Contents64::Raw(data),
        };

        self.dump.file.add_section(sec64);

        Ok(0)
    }
}

impl<'data> Output<'data> for ElfOutput<'data> {
    fn allocate(&mut self, size: u64) -> Result<u64, Error> {
        Ok(size)
    }

    fn append_section(&mut self, section: Section<'data>) -> Result<(), Error> {
        match section {
            Section::Text(si) => self.text.push(si),
            Section::Data(si) => self.data.push(si),
            Section::Bss(si) => self.bss.push(si),
        }

        Ok(())
    }

    fn finalize(mut self) -> Result<PathBuf, Error> {
        use std::io::Error as IOError;
        use std::io::ErrorKind;

        self.populate_section_data()?;
        let mut segment = Segment64::default();
        segment.header.set_type(Type::Load);
        self.dump.file.segments.push(segment);
        self.dump.file.finalize();

        let str_path = self.destination.to_str().ok_or_else(|| {
            let ioe = IOError::new(ErrorKind::Other, "Path expansion fail");
            let boxed = Box::new(ioe);
            Error::IOError(boxed)
        })?;

        self.dump
            .generate_elf_file(str_path, 0o755)
            .map_err(|e| Error::IOError(e))?;

        Ok(self.destination)
    }
}