/*
 * Copyright 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.compose.ui.text

import androidx.compose.runtime.Immutable
import androidx.compose.runtime.Stable
import androidx.compose.ui.text.style.Hyphens
import androidx.compose.ui.text.style.LineBreak
import androidx.compose.ui.text.style.LineHeightStyle
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.text.style.TextDirection
import androidx.compose.ui.text.style.TextIndent
import androidx.compose.ui.text.style.TextMotion
import androidx.compose.ui.text.style.lerp
import androidx.compose.ui.unit.LayoutDirection
import androidx.compose.ui.unit.TextUnit
import androidx.compose.ui.unit.isSpecified
import androidx.compose.ui.unit.isUnspecified

private val DefaultLineHeight = TextUnit.Unspecified

/**
 * Paragraph styling configuration for a paragraph. The difference between [SpanStyle] and
 * `ParagraphStyle` is that, `ParagraphStyle` can be applied to a whole [Paragraph] while
 * [SpanStyle] can be applied at the character level.
 * Once a portion of the text is marked with a `ParagraphStyle`, that portion will be separated from
 * the remaining as if a line feed character was added.
 *
 * @sample androidx.compose.ui.text.samples.ParagraphStyleSample
 * @sample androidx.compose.ui.text.samples.ParagraphStyleAnnotatedStringsSample
 *
 * @param textAlign The alignment of the text within the lines of the paragraph.
 * @param textDirection The algorithm to be used to resolve the final text direction:
 * Left To Right or Right To Left.
 * @param lineHeight Line height for the [Paragraph] in [TextUnit] unit, e.g. SP or EM.
 * @param textIndent The indentation of the paragraph.
 * @param platformStyle Platform specific [ParagraphStyle] parameters.
 * @param lineHeightStyle the configuration for line height such as vertical alignment of the
 * line, whether to apply additional space as a result of line height to top of first line top and
 * bottom of last line. The configuration is applied only when a [lineHeight] is defined.
 * When null, [LineHeightStyle.Default] is used.
 * @param lineBreak The line breaking configuration for the text.
 * @param hyphens The configuration of hyphenation.
 * @param textMotion Text character placement, whether to optimize for animated or static text.
 *
 * @see Paragraph
 * @see AnnotatedString
 * @see SpanStyle
 * @see TextStyle
 */
@Immutable
class ParagraphStyle(
    val textAlign: TextAlign = TextAlign.Unspecified,
    val textDirection: TextDirection = TextDirection.Unspecified,
    val lineHeight: TextUnit = TextUnit.Unspecified,
    val textIndent: TextIndent? = null,
    val platformStyle: PlatformParagraphStyle? = null,
    val lineHeightStyle: LineHeightStyle? = null,
    val lineBreak: LineBreak = LineBreak.Unspecified,
    val hyphens: Hyphens = Hyphens.Unspecified,
    val textMotion: TextMotion? = null
) {
    @Deprecated("Kept for backwards compatibility.", level = DeprecationLevel.WARNING)
    @get:JvmName("getTextAlign-buA522U") // b/320819734
    @Suppress("unused", "RedundantNullableReturnType", "PropertyName")
    val deprecated_boxing_textAlign: TextAlign? get() = this.textAlign

    @Deprecated("Kept for backwards compatibility.", level = DeprecationLevel.WARNING)
    @get:JvmName("getTextDirection-mmuk1to") // b/320819734
    @Suppress("unused", "RedundantNullableReturnType", "PropertyName")
    val deprecated_boxing_textDirection: TextDirection? get() = this.textDirection

    @Deprecated("Kept for backwards compatibility.", level = DeprecationLevel.WARNING)
    @get:JvmName("getHyphens-EaSxIns") // b/320819734
    @Suppress("unused", "RedundantNullableReturnType", "PropertyName")
    val deprecated_boxing_hyphens: Hyphens? get() = this.hyphens

    @Deprecated("Kept for backwards compatibility.", level = DeprecationLevel.WARNING)
    @get:JvmName("getLineBreak-LgCVezo") // b/320819734
    @Suppress("unused", "RedundantNullableReturnType", "PropertyName")
    val deprecated_boxing_lineBreak: LineBreak? get() = this.lineBreak

    @Deprecated("ParagraphStyle constructors that take nullable TextAlign, " +
        "TextDirection, LineBreak, and Hyphens are deprecated. Please use a new constructor " +
        "where these parameters are non-nullable. Null value has been replaced by a special " +
        "Unspecified object for performance reason.",
        level = DeprecationLevel.HIDDEN)
    constructor(
        textAlign: TextAlign? = null,
        textDirection: TextDirection? = null,
        lineHeight: TextUnit = TextUnit.Unspecified,
        textIndent: TextIndent? = null,
        platformStyle: PlatformParagraphStyle? = null,
        lineHeightStyle: LineHeightStyle? = null,
        lineBreak: LineBreak? = null,
        hyphens: Hyphens? = null,
        textMotion: TextMotion? = null
    ) : this(
        textAlign = textAlign ?: TextAlign.Unspecified,
        textDirection = textDirection ?: TextDirection.Unspecified,
        lineHeight = lineHeight,
        textIndent = textIndent,
        platformStyle = platformStyle,
        lineHeightStyle = lineHeightStyle,
        lineBreak = lineBreak ?: LineBreak.Unspecified,
        hyphens = hyphens ?: Hyphens.Unspecified,
        textMotion = textMotion
    )
    @Deprecated(
        "ParagraphStyle constructors that do not take new stable parameters " +
            "like LineHeightStyle, LineBreak, Hyphens are deprecated. Please use the new stable " +
            "constructor.",
        level = DeprecationLevel.HIDDEN
    )
    constructor(
        textAlign: TextAlign? = null,
        textDirection: TextDirection? = null,
        lineHeight: TextUnit = TextUnit.Unspecified,
        textIndent: TextIndent? = null
    ) : this(
        textAlign = textAlign ?: TextAlign.Unspecified,
        textDirection = textDirection ?: TextDirection.Unspecified,
        lineHeight = lineHeight,
        textIndent = textIndent,
        platformStyle = null,
        lineHeightStyle = null,
        lineBreak = LineBreak.Unspecified,
        hyphens = Hyphens.Unspecified,
        textMotion = null
    )

    @Deprecated(
        "ParagraphStyle constructors that do not take new stable parameters " +
            "like LineHeightStyle, LineBreak, Hyphens are deprecated. Please use the new stable " +
            "constructors.",
        level = DeprecationLevel.HIDDEN
    )
    constructor(
        textAlign: TextAlign? = null,
        textDirection: TextDirection? = null,
        lineHeight: TextUnit = TextUnit.Unspecified,
        textIndent: TextIndent? = null,
        platformStyle: PlatformParagraphStyle? = null,
        lineHeightStyle: LineHeightStyle? = null
    ) : this(
        textAlign = textAlign ?: TextAlign.Unspecified,
        textDirection = textDirection ?: TextDirection.Unspecified,
        lineHeight = lineHeight,
        textIndent = textIndent,
        platformStyle = platformStyle,
        lineHeightStyle = lineHeightStyle,
        lineBreak = LineBreak.Unspecified,
        hyphens = Hyphens.Unspecified,
        textMotion = null
    )

    @Deprecated(
        "ParagraphStyle constructors that do not take new stable parameters " +
            "like LineBreak, Hyphens, TextMotion are deprecated. Please use the new stable " +
            "constructors.",
        level = DeprecationLevel.HIDDEN
    )
    constructor(
        textAlign: TextAlign? = null,
        textDirection: TextDirection? = null,
        lineHeight: TextUnit = TextUnit.Unspecified,
        textIndent: TextIndent? = null,
        platformStyle: PlatformParagraphStyle? = null,
        lineHeightStyle: LineHeightStyle? = null,
        lineBreak: LineBreak? = null,
        hyphens: Hyphens? = null
    ) : this(
        textAlign = textAlign ?: TextAlign.Unspecified,
        textDirection = textDirection ?: TextDirection.Unspecified,
        lineHeight = lineHeight,
        textIndent = textIndent,
        platformStyle = platformStyle,
        lineHeightStyle = lineHeightStyle,
        lineBreak = lineBreak ?: LineBreak.Unspecified,
        hyphens = hyphens ?: Hyphens.Unspecified,
        textMotion = null
    )

    init {
        if (lineHeight != TextUnit.Unspecified) {
            // Since we are checking if it's negative, no need to convert Sp into Px at this point.
            check(lineHeight.value >= 0f) {
                "lineHeight can't be negative (${lineHeight.value})"
            }
        }
    }

    /**
     * Returns a new paragraph style that is a combination of this style and the given [other]
     * style.
     *
     * If the given paragraph style is null, returns this paragraph style.
     */
    @Stable
    fun merge(other: ParagraphStyle? = null): ParagraphStyle {
        if (other == null) return this

        return fastMerge(
            textAlign = other.textAlign,
            textDirection = other.textDirection,
            lineHeight = other.lineHeight,
            textIndent = other.textIndent,
            platformStyle = other.platformStyle,
            lineHeightStyle = other.lineHeightStyle,
            lineBreak = other.lineBreak,
            hyphens = other.hyphens,
            textMotion = other.textMotion
        )
    }

    /**
     * Plus operator overload that applies a [merge].
     */
    @Stable
    operator fun plus(other: ParagraphStyle): ParagraphStyle = this.merge(other)

    @Deprecated(
        "ParagraphStyle copy constructors that do not take new stable parameters " +
            "like LineHeightStyle, LineBreak, Hyphens are deprecated. Please use the new stable " +
            "copy constructor.",
        level = DeprecationLevel.HIDDEN
    )
    fun copy(
        textAlign: TextAlign? = this.textAlign,
        textDirection: TextDirection? = this.textDirection,
        lineHeight: TextUnit = this.lineHeight,
        textIndent: TextIndent? = this.textIndent
    ): ParagraphStyle {
        return ParagraphStyle(
            textAlign = textAlign ?: TextAlign.Unspecified,
            textDirection = textDirection ?: TextDirection.Unspecified,
            lineHeight = lineHeight,
            textIndent = textIndent,
            platformStyle = this.platformStyle,
            lineHeightStyle = this.lineHeightStyle,
            lineBreak = this.lineBreak,
            hyphens = this.hyphens,
            textMotion = this.textMotion
        )
    }

    @Deprecated(
        "ParagraphStyle copy constructors that do not take new stable parameters " +
            "like LineHeightStyle, LineBreak, Hyphens are deprecated. Please use the new stable " +
            "copy constructor.",
        level = DeprecationLevel.HIDDEN
    )
    fun copy(
        textAlign: TextAlign? = this.textAlign,
        textDirection: TextDirection? = this.textDirection,
        lineHeight: TextUnit = this.lineHeight,
        textIndent: TextIndent? = this.textIndent,
        platformStyle: PlatformParagraphStyle? = this.platformStyle,
        lineHeightStyle: LineHeightStyle? = this.lineHeightStyle
    ): ParagraphStyle {
        return ParagraphStyle(
            textAlign = textAlign ?: TextAlign.Unspecified,
            textDirection = textDirection ?: TextDirection.Unspecified,
            lineHeight = lineHeight,
            textIndent = textIndent,
            platformStyle = platformStyle,
            lineHeightStyle = lineHeightStyle,
            lineBreak = this.lineBreak,
            hyphens = this.hyphens,
            textMotion = this.textMotion
        )
    }

    @Deprecated(
        "ParagraphStyle copy constructors that do not take new stable parameters " +
            "like LineBreak, Hyphens, TextMotion are deprecated. Please use the new stable " +
            "copy constructor.",
        level = DeprecationLevel.HIDDEN
    )
    fun copy(
        textAlign: TextAlign? = this.textAlign,
        textDirection: TextDirection? = this.textDirection,
        lineHeight: TextUnit = this.lineHeight,
        textIndent: TextIndent? = this.textIndent,
        platformStyle: PlatformParagraphStyle? = this.platformStyle,
        lineHeightStyle: LineHeightStyle? = this.lineHeightStyle,
        lineBreak: LineBreak? = this.lineBreak,
        hyphens: Hyphens? = this.hyphens
    ): ParagraphStyle {
        return ParagraphStyle(
            textAlign = textAlign ?: TextAlign.Unspecified,
            textDirection = textDirection ?: TextDirection.Unspecified,
            lineHeight = lineHeight,
            textIndent = textIndent,
            platformStyle = platformStyle,
            lineHeightStyle = lineHeightStyle,
            lineBreak = lineBreak ?: LineBreak.Unspecified,
            hyphens = hyphens ?: Hyphens.Unspecified,
            textMotion = this.textMotion
        )
    }

    @Deprecated("ParagraphStyle copy constructors that take nullable TextAlign, " +
        "TextDirection, LineBreak, and Hyphens are deprecated. Please use a new constructor " +
        "where these parameters are non-nullable. Null value has been replaced by a special " +
        "Unspecified object for performance reason.",
        level = DeprecationLevel.HIDDEN)
    fun copy(
        textAlign: TextAlign? = this.textAlign,
        textDirection: TextDirection? = this.textDirection,
        lineHeight: TextUnit = this.lineHeight,
        textIndent: TextIndent? = this.textIndent,
        platformStyle: PlatformParagraphStyle? = this.platformStyle,
        lineHeightStyle: LineHeightStyle? = this.lineHeightStyle,
        lineBreak: LineBreak? = this.lineBreak,
        hyphens: Hyphens? = this.hyphens,
        textMotion: TextMotion? = this.textMotion
    ): ParagraphStyle {
        return ParagraphStyle(
            textAlign = textAlign ?: TextAlign.Unspecified,
            textDirection = textDirection ?: TextDirection.Unspecified,
            lineHeight = lineHeight,
            textIndent = textIndent,
            platformStyle = platformStyle,
            lineHeightStyle = lineHeightStyle,
            lineBreak = lineBreak ?: LineBreak.Unspecified,
            hyphens = hyphens ?: Hyphens.Unspecified,
            textMotion = textMotion
        )
    }

    fun copy(
        textAlign: TextAlign = this.textAlign,
        textDirection: TextDirection = this.textDirection,
        lineHeight: TextUnit = this.lineHeight,
        textIndent: TextIndent? = this.textIndent,
        platformStyle: PlatformParagraphStyle? = this.platformStyle,
        lineHeightStyle: LineHeightStyle? = this.lineHeightStyle,
        lineBreak: LineBreak = this.lineBreak,
        hyphens: Hyphens = this.hyphens,
        textMotion: TextMotion? = this.textMotion
    ): ParagraphStyle {
        return ParagraphStyle(
            textAlign = textAlign,
            textDirection = textDirection,
            lineHeight = lineHeight,
            textIndent = textIndent,
            platformStyle = platformStyle,
            lineHeightStyle = lineHeightStyle,
            lineBreak = lineBreak,
            hyphens = hyphens,
            textMotion = textMotion
        )
    }

    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (other !is ParagraphStyle) return false

        if (textAlign != other.textAlign) return false
        if (textDirection != other.textDirection) return false
        if (lineHeight != other.lineHeight) return false
        if (textIndent != other.textIndent) return false
        if (platformStyle != other.platformStyle) return false
        if (lineHeightStyle != other.lineHeightStyle) return false
        if (lineBreak != other.lineBreak) return false
        if (hyphens != other.hyphens) return false
        if (textMotion != other.textMotion) return false

        return true
    }

    override fun hashCode(): Int {
        var result = textAlign.hashCode()
        result = 31 * result + textDirection.hashCode()
        result = 31 * result + lineHeight.hashCode()
        result = 31 * result + (textIndent?.hashCode() ?: 0)
        result = 31 * result + (platformStyle?.hashCode() ?: 0)
        result = 31 * result + (lineHeightStyle?.hashCode() ?: 0)
        result = 31 * result + lineBreak.hashCode()
        result = 31 * result + hyphens.hashCode()
        result = 31 * result + (textMotion?.hashCode() ?: 0)
        return result
    }

    override fun toString(): String {
        return "ParagraphStyle(" +
            "textAlign=$textAlign, " +
            "textDirection=$textDirection, " +
            "lineHeight=$lineHeight, " +
            "textIndent=$textIndent, " +
            "platformStyle=$platformStyle, " +
            "lineHeightStyle=$lineHeightStyle, " +
            "lineBreak=$lineBreak, " +
            "hyphens=$hyphens, " +
            "textMotion=$textMotion" +
            ")"
    }
}

/**
 * Interpolate between two [ParagraphStyle]s.
 *
 * This will not work well if the styles don't set the same fields.
 *
 * The [fraction] argument represents position on the timeline, with 0.0 meaning
 * that the interpolation has not started, returning [start] (or something
 * equivalent to [start]), 1.0 meaning that the interpolation has finished,
 * returning [stop] (or something equivalent to [stop]), and values in between
 * meaning that the interpolation is at the relevant point on the timeline
 * between [start] and [stop]. The interpolation can be extrapolated beyond 0.0 and
 * 1.0, so negative values and values greater than 1.0 are valid.
 */
@Stable
fun lerp(start: ParagraphStyle, stop: ParagraphStyle, fraction: Float): ParagraphStyle {
    return ParagraphStyle(
        textAlign = lerpDiscrete(start.textAlign, stop.textAlign, fraction),
        textDirection = lerpDiscrete(
            start.textDirection,
            stop.textDirection,
            fraction
        ),
        lineHeight = lerpTextUnitInheritable(start.lineHeight, stop.lineHeight, fraction),
        textIndent = lerp(
            start.textIndent ?: TextIndent.None,
            stop.textIndent ?: TextIndent.None,
            fraction
        ),
        platformStyle = lerpPlatformStyle(start.platformStyle, stop.platformStyle, fraction),
        lineHeightStyle = lerpDiscrete(
            start.lineHeightStyle,
            stop.lineHeightStyle,
            fraction
        ),
        lineBreak = lerpDiscrete(start.lineBreak, stop.lineBreak, fraction),
        hyphens = lerpDiscrete(start.hyphens, stop.hyphens, fraction),
        textMotion = lerpDiscrete(start.textMotion, stop.textMotion, fraction)
    )
}

private fun lerpPlatformStyle(
    start: PlatformParagraphStyle?,
    stop: PlatformParagraphStyle?,
    fraction: Float
): PlatformParagraphStyle? {
    if (start == null && stop == null) return null
    val startNonNull = start ?: PlatformParagraphStyle.Default
    val stopNonNull = stop ?: PlatformParagraphStyle.Default
    return lerp(startNonNull, stopNonNull, fraction)
}

internal fun resolveParagraphStyleDefaults(
    style: ParagraphStyle,
    direction: LayoutDirection
) = ParagraphStyle(
    textAlign = if (style.textAlign == TextAlign.Unspecified) TextAlign.Start else style.textAlign,
    textDirection = resolveTextDirection(direction, style.textDirection),
    lineHeight = if (style.lineHeight.isUnspecified) DefaultLineHeight else style.lineHeight,
    textIndent = style.textIndent ?: TextIndent.None,
    platformStyle = style.platformStyle,
    lineHeightStyle = style.lineHeightStyle,
    lineBreak = if (style.lineBreak == LineBreak.Unspecified) LineBreak.Simple else style.lineBreak,
    hyphens = if (style.hyphens == Hyphens.Unspecified) Hyphens.None else style.hyphens,
    textMotion = style.textMotion ?: TextMotion.Static
)

 internal fun ParagraphStyle.fastMerge(
    textAlign: TextAlign,
    textDirection: TextDirection,
    lineHeight: TextUnit,
    textIndent: TextIndent?,
    platformStyle: PlatformParagraphStyle?,
    lineHeightStyle: LineHeightStyle?,
    lineBreak: LineBreak,
    hyphens: Hyphens,
    textMotion: TextMotion?
): ParagraphStyle {
     // prioritize the parameters to Text in diffs here
     /**
      *  textAlign: TextAlign?
      *  lineHeight: TextUnit
      */

     // any new vals should do a pre-merge check here
     val requiresAlloc = textAlign != TextAlign.Unspecified && textAlign != this.textAlign ||
         lineHeight.isSpecified && lineHeight != this.lineHeight ||
         textIndent != null && textIndent != this.textIndent ||
         textDirection != TextDirection.Unspecified && textDirection != this.textDirection ||
         platformStyle != null && platformStyle != this.platformStyle ||
         lineHeightStyle != null && lineHeightStyle != this.lineHeightStyle ||
         lineBreak != LineBreak.Unspecified && lineBreak != this.lineBreak ||
         hyphens != Hyphens.Unspecified && hyphens != this.hyphens ||
         textMotion != null && textMotion != this.textMotion

     if (!requiresAlloc) {
         return this
     }

     return ParagraphStyle(
         lineHeight = if (lineHeight.isUnspecified) {
             this.lineHeight
         } else {
             lineHeight
         },
         textIndent = textIndent ?: this.textIndent,
         textAlign = if (textAlign != TextAlign.Unspecified) textAlign else this.textAlign,
         textDirection =
         if (textDirection != TextDirection.Unspecified) textDirection else this.textDirection,
         platformStyle = mergePlatformStyle(platformStyle),
         lineHeightStyle = lineHeightStyle ?: this.lineHeightStyle,
         lineBreak = if (lineBreak != LineBreak.Unspecified) lineBreak else this.lineBreak,
         hyphens = if (hyphens != Hyphens.Unspecified) hyphens else this.hyphens,
         textMotion = textMotion ?: this.textMotion
     )
}

private fun ParagraphStyle.mergePlatformStyle(
    other: PlatformParagraphStyle?
): PlatformParagraphStyle? {
    if (platformStyle == null) return other
    if (other == null) return platformStyle
    return platformStyle.merge(other)
}