use super::*;

const DATA_SPACE_SIZE : usize = 12 * 1024 * 1024; // 16MB

lazy_static! {
    static ref DATA_SPACE: SgxMutex<VMSpace> = {
        let size = DATA_SPACE_SIZE;
        let addr = {
            let ptr = unsafe { aligned_malloc(size, PAGE_SIZE) };
            if ptr == (0 as *mut c_void) {
                panic!("Out of memory");
            };
            ptr as usize
        };
        let vm_space = unsafe {
            match VMSpace::new(addr, size, VMGuardAreaType::None) {
                Ok(vm_space) => vm_space,
                Err(_) => panic!("Failed to create a VMSpace"),
            }
        };
        SgxMutex::new(vm_space)
    };
}

unsafe fn aligned_malloc(mem_size: usize, mem_align: usize) -> *mut c_void {
    let mut mem_ptr = ::core::ptr::null_mut();
    let ret = libc::posix_memalign(&mut mem_ptr, mem_align, mem_size);
    if ret == 0 {
        mem_ptr
    } else {
        0 as *mut c_void
    }
}

#[derive(Debug)]
pub struct ProcessVM {
    //code_domain: VMDomain,
    data_domain: VMDomain,
    code_vma: VMArea,
    data_vma: VMArea,
    heap_vma: VMArea,
    stack_vma: VMArea,
    mmap_vmas: Vec<Box<VMArea>>,
}

impl ProcessVM {
    pub fn new(code_size: usize, data_size: usize,
               heap_size: usize, stack_size: usize,
               mmap_size: usize)
        -> Result<ProcessVM, Error>
    {
        let data_domain_size = code_size + data_size + heap_size + stack_size + mmap_size;
        let mut data_domain = DATA_SPACE.lock().unwrap().
            alloc_domain(data_domain_size)?;

        let (code_vma, data_vma, heap_vma, stack_vma) =
            ProcessVM::alloc_vmas(&mut data_domain, code_size, data_size,
                                 heap_size, stack_size)?;
        // No mmapped vmas initially
        let mmap_vmas = Vec::new();

        Ok(ProcessVM {
            data_domain,
            code_vma,
            data_vma,
            heap_vma,
            stack_vma,
            mmap_vmas,
        })
    }

    fn alloc_vmas(data_domain: &mut VMDomain,
                  code_size: usize, data_size: usize,
                  heap_size: usize, stack_size: usize)
        -> Result<(VMArea, VMArea, VMArea, VMArea), Error>
    {
        let mut addr = data_domain.get_start();

        let mut alloc_vma_continuously = |addr: &mut usize, size, flags, growth| -> Result<_, Error> {
            let mut options = VMAllocOptions::new(size)?;
            options.addr(VMAddrOption::Fixed(*addr))?.growth(growth)?;
            let new_vma = data_domain.alloc_area(&options, flags)?;
            *addr += size;
            Ok(new_vma)
        };

        let rx_flags = VMAreaFlags(VM_AREA_FLAG_R | VM_AREA_FLAG_X);
        let rw_flags = VMAreaFlags(VM_AREA_FLAG_R | VM_AREA_FLAG_W);

        let code_vma = alloc_vma_continuously(&mut addr,
                                              code_size, rx_flags,
                                              VMGrowthType::Fixed)?;
        let data_vma = alloc_vma_continuously(&mut addr,
                                              data_size, rw_flags,
                                              VMGrowthType::Fixed)?;
        let heap_vma = alloc_vma_continuously(&mut addr,
                                              0, rw_flags,
                                              VMGrowthType::Upward)?;
        // Preserve the space for heap
        addr += heap_size;
        // After the heap is the stack
        let stack_vma = alloc_vma_continuously(&mut addr,
                                               stack_size, rw_flags,
                                               VMGrowthType::Downward)?;
        Ok((code_vma, data_vma, heap_vma, stack_vma))
    }

    pub fn get_base_addr(&self) -> usize {
        self.code_vma.get_start()
    }

    pub fn get_code_vma(&self) -> &VMArea {
        &self.code_vma
    }

    pub fn get_data_vma(&self) -> &VMArea {
        &self.data_vma
    }

    pub fn get_heap_vma(&self) -> &VMArea {
        &self.heap_vma
    }

    pub fn get_stack_vma(&self) -> &VMArea {
        &self.stack_vma
    }

    pub fn get_stack_top(&self) -> usize {
        self.stack_vma.get_end()
    }

    pub fn get_mmap_vmas(&self) -> &[Box<VMArea>] {
        &self.mmap_vmas[..]
    }

    pub fn get_brk_start(&self) -> usize {
        self.get_heap_vma().get_start()
    }

    pub fn get_brk(&self) -> usize {
        self.get_heap_vma().get_end()
    }

    pub fn get_mmap_start(&self) -> usize {
        self.get_stack_vma().get_end()
    }

    pub fn mmap(&mut self, addr: usize, size: usize, flags: VMAreaFlags)
        -> Result<usize, Error>
    {
        let alloc_options = {
            let mmap_start_addr = self.get_mmap_start();

            let mut alloc_options = VMAllocOptions::new(size)?;
            alloc_options.addr(
                if addr == 0 {
                    VMAddrOption::Beyond(mmap_start_addr)
                }
                else {
                    if addr < mmap_start_addr {
                        return Err(Error::new(Errno::EINVAL,
                                              "Beyond valid memory range"));
                    }
                    VMAddrOption::Fixed(addr)
                }
            )?.growth(VMGrowthType::Upward)?;
            alloc_options
        };
        // TODO: when failed, try to resize data_domain
        let new_mmap_vma = self.data_domain.alloc_area(&alloc_options, flags)?;
        let addr = new_mmap_vma.get_start();
        self.mmap_vmas.push(Box::new(new_mmap_vma));
        Ok(addr)
    }

    pub fn munmap(&mut self, addr: usize, size: usize)
        -> Result<(), Error>
    {
        // TODO: handle the case when the given range [addr, addr + size)
        // does not match exactly with any vma. For example, when this range
        // cover multiple ranges or cover some range partially.

        let mmap_vma_i = {
            let mmap_vma_i = self.get_mmap_vmas().iter().position(|vma| {
                    vma.get_start() == addr && vma.get_end() == addr + size
                });
            if mmap_vma_i.is_none() { return Ok(()) }
            mmap_vma_i.unwrap()
        };

        let mut removed_mmap_vma = self.mmap_vmas.swap_remove(mmap_vma_i);
        self.data_domain.dealloc_area(&mut removed_mmap_vma);
        Ok(())
    }

    pub fn mremap(&mut self, old_addr: usize, old_size: usize,
                  options: &VMResizeOptions)
        -> Result<usize, Error>
    {
        // TODO: Implement this!
        Err(Error::new(Errno::EINVAL, "Not implemented"))
    }

    pub fn brk(&mut self, new_brk: usize) -> Result<usize, Error> {
        if new_brk == 0 {
            return Ok(self.get_brk());
        }

        let resize_options = {
            let brk_start = self.get_brk_start();

            let new_heap_size = {
                if new_brk < brk_start {
                    return Err(Error::new(Errno::EINVAL, "Invalid brk"));
                }
                new_brk - brk_start
            };

            let mut options = VMResizeOptions::new(new_heap_size)?;
            options.addr(VMAddrOption::Fixed(brk_start));
            options
        };
        self.data_domain.resize_area(&mut self.heap_vma, &resize_options)?;
        Ok(new_brk)
    }
}


impl Drop for ProcessVM {
    fn drop(&mut self) {
        let data_domain = &mut self.data_domain;

        // Remove all vma from the domain
        data_domain.dealloc_area(&mut self.code_vma);
        data_domain.dealloc_area(&mut self.data_vma);
        data_domain.dealloc_area(&mut self.heap_vma);
        data_domain.dealloc_area(&mut self.stack_vma);
        for mmap_vma in &mut self.mmap_vmas {
            data_domain.dealloc_area(mmap_vma);
        }

        // Remove the domain from its parent space
        DATA_SPACE.lock().unwrap().dealloc_domain(data_domain);
    }
}