use crate::ffi::wchar_t;
use crate::{ffi, Error, LCMSResult, Locale};
use foreign_types::{foreign_type, ForeignType, ForeignTypeRef};
use std::char::{decode_utf16, REPLACEMENT_CHARACTER};
use std::ffi::CString;
use std::fmt;
use std::mem;
use std::ptr;

foreign_type! {
    /// This represents owned Multi Localized Unicode type. Most methods are implemented on `MLURef`.
    /// This is a borrwed Multi Localized Unicode type. It holds Unicode strings associated with `Locale`.
    pub unsafe type MLU {
        type CType = ffi::MLU;
        fn drop = ffi::cmsMLUfree;
    }
}

impl MLU {
    /// Allocates an empty multilocalized unicode object.
    #[track_caller]
    #[inline]
    #[must_use]
    pub fn new(items: usize) -> Self {
        unsafe {
            let handle = ffi::cmsMLUalloc(ptr::null_mut(), items as u32);
            assert!(!handle.is_null());
            MLU::from_ptr(handle)
        }
    }
}

impl MLURef {
    /// Fills an ASCII (7 bit) entry for the given Language and country.
    pub fn set_text_ascii(&mut self, text: &str, locale: Locale) -> bool {
        let Ok(cstr) = CString::new(text) else { return false };
        unsafe {
            ffi::cmsMLUsetASCII(
                (self as *mut Self).cast(),
                locale.language_ptr(),
                locale.country_ptr(),
                cstr.as_ptr(),
            ) != 0
        }
    }

    /// Fills a UNICODE wide char (16 bit) entry for the given Language and country.
    pub fn set_text(&mut self, text: &str, locale: Locale) -> bool {
        let chars: Vec<_> = text
            .chars()
            .map(|c| c as wchar_t)
            .chain([0 as wchar_t])
            .collect();

        unsafe {
            ffi::cmsMLUsetWide(
                (self as *mut Self).cast(),
                locale.language_ptr(),
                locale.country_ptr(),
                chars[..].as_ptr(),
            ) != 0
        }
    }

    /// Gets an ASCII (7 bit) entry for the given Language and country.
    pub fn text_ascii(&self, locale: Locale) -> LCMSResult<String> {
        let len = unsafe {
            ffi::cmsMLUgetASCII(
                self.as_ptr(),
                locale.language_ptr(),
                locale.country_ptr(),
                ptr::null_mut(),
                0,
            )
        };
        if len == 0 {
            return Err(Error::MissingData);
        }
        let mut buf = vec![0u8; len as usize];
        unsafe {
            ffi::cmsMLUgetASCII(
                self.as_ptr(),
                locale.language_ptr(),
                locale.country_ptr(),
                buf[..].as_mut_ptr().cast(),
                len,
            );
            if let Some(0) = buf.pop() { // terminating zero
                String::from_utf8(buf).map_err(|_| Error::InvalidString)
            } else {
                Err(Error::InvalidString)
            }
        }
    }

    /// Gets a Unicode entry for the given Language and country
    pub fn text(&self, locale: Locale) -> LCMSResult<String> {
        let len_bytes = unsafe {
            ffi::cmsMLUgetWide(
                self.as_ptr(),
                locale.language_ptr(),
                locale.country_ptr(),
                ptr::null_mut(),
                0,
            )
        };
        let len_wchars = len_bytes as usize / mem::size_of::<wchar_t>();
        if len_wchars == 0 || (len_bytes & 1) != 0 {
            return Err(Error::MissingData);
        }
        let mut buf = vec![0 as wchar_t; len_wchars];
        unsafe {
            ffi::cmsMLUgetWide(
                self.as_ptr(),
                locale.language_ptr(),
                locale.country_ptr(),
                buf[..].as_mut_ptr().cast::<wchar_t>(),
                len_bytes,
            );
            if let Some(0) = buf.pop() { // terminating zero
                Ok(decode_utf16(buf.into_iter().map(|c| c as u16))
                    .map(|r| r.unwrap_or(REPLACEMENT_CHARACTER))
                    .collect())
            } else {
                Err(Error::InvalidString)
            }
        }
    }

    /// Obtains the translations stored in a given multilocalized unicode object.
    #[must_use]
    pub fn tanslations(&self) -> Vec<Locale> {
        let count = unsafe { ffi::cmsMLUtranslationsCount(self.as_ptr()) };
        let mut out = vec![Locale::none(); count as usize];

        let mut i = 0;
        out.retain_mut(|locale| {
            let ok = unsafe {
                ffi::cmsMLUtranslationsCodes(
                    self.as_ptr(),
                    i,
                    locale.language_ptr_mut(),
                    locale.country_ptr_mut(),
                ) != 0
            };
            i += 1;
            ok
        });
        out
    }

    /// Obtains the translation rule for given multilocalized unicode object.
    pub fn tanslation(&self, locale: Locale) -> LCMSResult<Locale> {
        let mut out = Locale::none();
        if unsafe {
            ffi::cmsMLUgetTranslation(
                self.as_ptr(),
                locale.language_ptr(),
                locale.country_ptr(),
                out.language_ptr_mut(),
                out.country_ptr_mut(),
            ) != 0
        } {
            Ok(out)
        } else {
            Err(Error::MissingData)
        }
    }
}

impl fmt::Debug for MLURef {
    #[cold]
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let t = self.text(Locale::none());
        write!(
            f,
            "MLU({:?} {:?})",
            if let Ok(ref t) = t { t } else { "None" },
            self.tanslations()
        )
    }
}

#[test]
fn mlu() {
    let _ = MLU::new(0);
    let mut m = MLU::new(1);
    assert!(m.set_text("Hello 世界！", Locale::none()));
    assert_eq!(Ok("Hello 世界！".to_owned()), m.text(Locale::none()));
    assert!(!m.set_text_ascii("エッロル", Locale::none()));

    assert!(m.set_text("a", Locale::new("en_US")));
    assert_eq!("a", m.text_ascii(Locale::new("en_US")).unwrap());

    let mut m = MLU::new(1);
    assert!(m.set_text_ascii("OK", Locale::none()));
    assert_eq!("OK", m.text_ascii(Locale::none()).unwrap());
}