use std::borrow::Cow;
use super::exifreadable::*;
use super::types::*;

type ReadableFn = fn(&TagValue) -> Option<Cow<'static, str>>;

/// Convert a numeric tag into ExifTag enumeration, and yields information about the tag. This information
/// is used by the main body of the parser to sanity-check the tags found in image
/// and make sure that EXIF tags have the right data types
///
/// Returns (tag, unit, format, min_count, max_count, more_readable)
pub fn tag_to_exif(f: u16) -> (ExifTag, &'static str, IfdFormat, i32, i32, ReadableFn)
{
    match f {

        0x010e =>
        (ExifTag::ImageDescription, "none", IfdFormat::Ascii,
        -1i32, -1i32, strpass),

        0x010f =>
        (ExifTag::Make, "none", IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x013c =>
        (ExifTag::HostComputer, "none", IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x0110 =>
        (ExifTag::Model, "none", IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x0112 =>
        (ExifTag::Orientation, "none", IfdFormat::U16, 1, 1, orientation),

        0x011a =>
        (ExifTag::XResolution, "pixels per res unit",
        IfdFormat::URational, 1, 1, rational_value),

        0x011b =>
        (ExifTag::YResolution, "pixels per res unit",
        IfdFormat::URational, 1, 1, rational_value),

        0x0128 =>
        (ExifTag::ResolutionUnit, "none", IfdFormat::U16, 1, 1, resolution_unit),

        0x0131 =>
        (ExifTag::Software, "none", IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x0132 =>
        (ExifTag::DateTime, "none", IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x013e =>
        (ExifTag::WhitePoint, "CIE 1931 coordinates",
        IfdFormat::URational, 2, 2, rational_values),

        0x013f =>
        (ExifTag::PrimaryChromaticities, "CIE 1931 coordinates",
        IfdFormat::URational, 6, 6, rational_values),

        0x0211 =>
        (ExifTag::YCbCrCoefficients, "none",
        IfdFormat::URational, 3, 3, rational_values),

        0x0214 =>
        (ExifTag::ReferenceBlackWhite, "RGB or YCbCr",
        IfdFormat::URational, 6, 6, rational_values),

        0x8298 =>
        (ExifTag::Copyright, "none", IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x8769 =>
        (ExifTag::ExifOffset, "byte offset",
        IfdFormat::U32, 1, 1, strpass),

        0x8825 =>
        (ExifTag::GPSOffset, "byte offset",
        IfdFormat::U32, 1, 1, strpass),

        0x829a =>
        (ExifTag::ExposureTime, "s",
        IfdFormat::URational, 1, 1, exposure_time),

        0x829d =>
        (ExifTag::FNumber, "f-number",
        IfdFormat::URational, 1, 1, f_number),

        0x8822 =>
        (ExifTag::ExposureProgram, "none",
        IfdFormat::U16, 1, 1, exposure_program),

        0x8824 =>
        (ExifTag::SpectralSensitivity, "ASTM string",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x8830 =>
        (ExifTag::SensitivityType, "none",
        IfdFormat::U16, 1, 1, sensitivity_type),

        0x8827 =>
        (ExifTag::ISOSpeedRatings, "ISO",
        IfdFormat::U16, 1, 3, iso_speeds),

        0x8828 =>
        (ExifTag::OECF, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_blob),

        0x9000 =>
        (ExifTag::ExifVersion, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_ascii),

        0x9003 =>
        (ExifTag::DateTimeOriginal, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x9004 =>
        (ExifTag::DateTimeDigitized, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x9201 =>
        (ExifTag::ShutterSpeedValue, "APEX",
        IfdFormat::IRational, 1, 1, apex_tv),

        0x9202 =>
        (ExifTag::ApertureValue, "APEX",
        IfdFormat::URational, 1, 1, apex_av),

        0x9203 =>
        (ExifTag::BrightnessValue, "APEX",
        IfdFormat::IRational, 1, 1, apex_brightness),

        0x9204 =>
        (ExifTag::ExposureBiasValue, "APEX",
        IfdFormat::IRational, 1, 1, apex_ev),

        0x9205 =>
        (ExifTag::MaxApertureValue,
        "APEX", IfdFormat::URational, 1, 1, apex_av),

        0x9206 =>
        (ExifTag::SubjectDistance, "m",
        IfdFormat::URational, 1, 1, meters),

        0x9207 =>
        (ExifTag::MeteringMode, "none",
        IfdFormat::U16, 1, 1, metering_mode),

        0x9208 =>
        (ExifTag::LightSource, "none",
        IfdFormat::U16, 1, 1, light_source),

        0x9209 => (ExifTag::Flash, "none",
        IfdFormat::U16, 1, 2, flash),

        0x920a =>
        (ExifTag::FocalLength, "mm",
        IfdFormat::URational, 1, 1, focal_length),

        0x9214 =>
        (ExifTag::SubjectArea, "px",
        IfdFormat::U16, 2, 4, subject_area),

        0x927c =>
        (ExifTag::MakerNote, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_blob),

        0x9286 =>
        (ExifTag::UserComment, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_encoded_string),

        0xa000 =>
        (ExifTag::FlashPixVersion, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_ascii),

        0xa001 =>
        (ExifTag::ColorSpace, "none",
        IfdFormat::U16, 1, 1, color_space),

        0xa004 =>
        (ExifTag::RelatedSoundFile, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0xa20b => (ExifTag::FlashEnergy, "BCPS",
        IfdFormat::URational, 1, 1, flash_energy),

        0xa20e =>
        (ExifTag::FocalPlaneXResolution, "@FocalPlaneResolutionUnit",
        IfdFormat::URational, 1, 1, rational_value),

        0xa20f =>
        (ExifTag::FocalPlaneYResolution, "@FocalPlaneResolutionUnit",
        IfdFormat::URational, 1, 1, rational_value),

        0xa210 =>
        (ExifTag::FocalPlaneResolutionUnit, "none",
        IfdFormat::U16, 1, 1, resolution_unit),

        0xa214 =>
        (ExifTag::SubjectLocation, "X,Y",
        IfdFormat::U16, 2, 2, subject_location),

        // TODO check if rational as decimal value is the best for this one
        0xa215 =>
        (ExifTag::ExposureIndex, "EI",
        IfdFormat::URational, 1, 1, rational_value),

        0xa217 =>
        (ExifTag::SensingMethod, "none",
        IfdFormat::U16, 1, 1, sensing_method),

        0xa300 =>
        (ExifTag::FileSource, "none",
        IfdFormat::Undefined, 1, 1, file_source),

        0xa301 =>
        (ExifTag::SceneType, "none",
        IfdFormat::Undefined, 1, 1, scene_type),

        0xa302 =>
        (ExifTag::CFAPattern, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_u8),

        0xa401 =>
        (ExifTag::CustomRendered, "none",
        IfdFormat::U16, 1, 1, custom_rendered),

        0xa402 =>
        (ExifTag::ExposureMode, "none",
        IfdFormat::U16, 1, 1, exposure_mode),

        0xa403 =>
        (ExifTag::WhiteBalanceMode, "none",
        IfdFormat::U16, 1, 1, white_balance_mode),

        0xa404 =>
        (ExifTag::DigitalZoomRatio, "none",
        IfdFormat::URational, 1, 1, rational_value),

        0xa405 =>
        (ExifTag::FocalLengthIn35mmFilm, "mm",
        IfdFormat::U16, 1, 1, focal_length_35),

        0xa406 =>
        (ExifTag::SceneCaptureType, "none",
        IfdFormat::U16, 1, 1, scene_capture_type),

        0xa407 =>
        (ExifTag::GainControl, "none",
        IfdFormat::U16, 1, 1, gain_control),

        0xa408 =>
        (ExifTag::Contrast, "none",
        IfdFormat::U16, 1, 1, contrast),

        0xa409 =>
        (ExifTag::Saturation, "none",
        IfdFormat::U16, 1, 1, saturation),

        0xa40a =>
        (ExifTag::Sharpness, "none",
        IfdFormat::U16, 1, 1, sharpness),

        0xa432 =>
        (ExifTag::LensSpecification, "none",
        IfdFormat::URational, 4, 4, lens_spec),

        0xa433 =>
        (ExifTag::LensMake, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0xa434 =>
        (ExifTag::LensModel, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0xa500 =>
        (ExifTag::Gamma, "none",
        IfdFormat::URational, 1, 1, rational_value),

        // collaborate if you have any idea how to interpret this
        0xa40b =>
        (ExifTag::DeviceSettingDescription, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_blob),

        0xa40c =>
        (ExifTag::SubjectDistanceRange, "none",
        IfdFormat::U16, 1, 1, subject_distance_range),

        0xa420 =>
        (ExifTag::ImageUniqueID, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x0 =>
        (ExifTag::GPSVersionID, "none",
        IfdFormat::U8, 4, 4, strpass),

        0x1 =>
        (ExifTag::GPSLatitudeRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x2 =>
        (ExifTag::GPSLatitude, "D/M/S",
        IfdFormat::URational, 3, 3, dms),

        0x3 =>
        (ExifTag::GPSLongitudeRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x4 =>
        (ExifTag::GPSLongitude, "D/M/S",
        IfdFormat::URational, 3, 3, dms),

        0x5 =>
        (ExifTag::GPSAltitudeRef, "none",
        IfdFormat::U8, 1, 1, gps_alt_ref),

        0x6 =>
        (ExifTag::GPSAltitude, "m",
        IfdFormat::URational, 1, 1, meters),

        0x7 =>
        (ExifTag::GPSTimeStamp, "UTC time",
        IfdFormat::URational, 3, 3, gpstimestamp),

        0x8 => (ExifTag::GPSSatellites, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x9 => (ExifTag::GPSStatus, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsstatus),

        0xa => (ExifTag::GPSMeasureMode, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsmeasuremode),

        0xb =>
        (ExifTag::GPSDOP, "none",
        IfdFormat::URational, 1, 1, rational_value),

        0xc =>
        (ExifTag::GPSSpeedRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsspeedref),

        0xd =>
        (ExifTag::GPSSpeed, "@GPSSpeedRef",
        IfdFormat::URational, 1, 1, gpsspeed),

        0xe =>
        (ExifTag::GPSTrackRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsbearingref),

        0xf =>
        (ExifTag::GPSTrack, "deg",
        IfdFormat::URational, 1, 1, gpsbearing),

        0x10 =>
        (ExifTag::GPSImgDirectionRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsbearingref),

        0x11 =>
        (ExifTag::GPSImgDirection, "deg",
        IfdFormat::URational, 1, 1, gpsbearing),

        0x12 =>
        (ExifTag::GPSMapDatum, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x13 =>
        (ExifTag::GPSDestLatitudeRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x14 =>
        (ExifTag::GPSDestLatitude, "D/M/S",
        IfdFormat::URational, 3, 3, dms),

        0x15 =>
        (ExifTag::GPSDestLongitudeRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x16 =>
        (ExifTag::GPSDestLongitude, "D/M/S",
        IfdFormat::URational, 3, 3, dms),

        0x17 =>
        (ExifTag::GPSDestBearingRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsbearingref),

        0x18 =>
        (ExifTag::GPSDestBearing, "deg",
        IfdFormat::URational, 1, 1, gpsbearing),

        0x19 =>
        (ExifTag::GPSDestDistanceRef, "none",
        IfdFormat::Ascii, -1i32, -1i32, gpsdestdistanceref),

        0x1a =>
        (ExifTag::GPSDestDistance, "@GPSDestDistanceRef",
        IfdFormat::URational, 1, 1, gpsdestdistance),

        0x1b =>
        (ExifTag::GPSProcessingMethod, "none",
        IfdFormat::Undefined, -1i32, -1i32, undefined_as_encoded_string),

        0x1c => (ExifTag::GPSAreaInformation,
        "none", IfdFormat::Undefined, -1i32, -1i32, undefined_as_encoded_string),

        0x1d =>
        (ExifTag::GPSDateStamp, "none",
        IfdFormat::Ascii, -1i32, -1i32, strpass),

        0x1e =>
        (ExifTag::GPSDifferential, "none",
        IfdFormat::U16, 1, 1, gpsdiff),

        _ =>
        (ExifTag::UnknownToMe, "Unknown unit",
        IfdFormat::Unknown, -1i32, -1i32, nop)
    }
}