// Standard components

package ui

import "unicode"

// Status bar component.  This component displays text on the left and right of it's
// allocated space.
type StatusBar struct {
    Left    string          // Left aligned string
    Right   string          // Right aligned string
}

// Minimum dimensions
func (sbar *StatusBar) Remeasure(w, h int) (int, int) {
    return w, 1
}

// Status bar redraw
func (sbar *StatusBar) Redraw(context *DrawContext) {
    context.SetFgAttr(AttrReverse)
    context.SetBgAttr(AttrReverse)

    context.HorizRule(0, ' ')
    context.Print(0, 0, sbar.Left)
    context.PrintRight(context.W, 0, sbar.Right)
}


// A single-text entry component.
type TextEntry struct {
    Prompt          string

    value           string
    cursorOffset    int
    displayOffset   int
}

func (te *TextEntry) Remeasure(w, h int) (int, int) {
    return w, 1
}

func (te *TextEntry) Redraw(context *DrawContext) {
    context.HorizRule(0, ' ')
    valueOffsetX := 0
    displayOffsetX := te.calculateDisplayOffset(context.W)

    if te.Prompt != "" {
        context.SetFgAttr(ColorDefault | AttrBold)
        context.Print(0, 0, te.Prompt)
        context.SetFgAttr(ColorDefault)

        valueOffsetX = len(te.Prompt)
    }

    context.Print(valueOffsetX, 0, te.value[displayOffsetX:intMin(displayOffsetX + context.W,len(te.value))])
    context.SetCursorPosition(te.cursorOffset + valueOffsetX - displayOffsetX, 0)

    //context.Print(0, 0, fmt.Sprintf("%d,%d", te.cursorOffset, displayOffsetX))
}

func (te *TextEntry) calculateDisplayOffset(displayWidth int) int {
    if te.Prompt != "" {
        displayWidth -= len(te.Prompt)
    }
    virtualCursorOffset := te.cursorOffset - te.displayOffset

    if virtualCursorOffset >= displayWidth {
        te.displayOffset = te.cursorOffset - displayWidth + 10
    } else if (virtualCursorOffset < 0) {
        te.displayOffset = intMax(te.cursorOffset - displayWidth + 1, 0)
    }

    return te.displayOffset
}

func (te *TextEntry) KeyPressed(key rune, mod int) {
    if (key >= ' ') && (key <= '~') {
        te.insertRune(key)
    } else if (key == KeyArrowLeft) {
        te.moveCursorBy(-1)
    } else if (key == KeyArrowRight) {
        te.moveCursorBy(1)
    } else if (key == KeyHome) {
        te.moveCursorTo(0)
    } else if (key == KeyEnd) {
        te.moveCursorTo(len(te.value))
    } else if (key == KeyBackspace) || (key == KeyBackspace2) {
        if (mod & ModKeyAlt != 0) {
            te.backspaceWhile(unicode.IsSpace)
            te.backspaceWhile(func(r rune) bool { return !unicode.IsSpace(r) })
        } else {
            te.backspace()
        }
    } else if (key == KeyCtrlK) {
        te.killLine()
    } else if (key == KeyDelete) {
        te.removeCharAtPos(te.cursorOffset)
    } else if (key == KeyEnter) {
        panic("Entered text: '" + te.value + "'")
    }
}

// Backspace
func (te *TextEntry) backspace() {
    te.removeCharAtPos(te.cursorOffset - 1)
    te.moveCursorBy(-1)    
}

// Backspace while the character underneith the cursor matches the guard
func (te *TextEntry) backspaceWhile(guard func(r rune) bool) {
    for (te.cursorOffset > 0) {
        ch := rune(te.value[te.cursorOffset - 1])
        if guard(ch) {
            te.backspace()
        } else {
            break
        }
    }
}

// Kill the line.  If the cursor is at the end of the line, kill to the start.
// Otherwise, trim the line.
func (te *TextEntry) killLine() {
    if (te.cursorOffset < len(te.value)) {
        te.value = te.value[:te.cursorOffset]
    } else {
        te.value = ""
        te.cursorOffset = 0
    }
}

// Inserts a rune at the cursor position
func (te *TextEntry) insertRune(key rune) {
    if (te.cursorOffset >= len(te.value)) {
        te.value += string(key)
    } else {
        te.value = te.value[:te.cursorOffset] + string(key) + te.value[te.cursorOffset:]
    }
    te.moveCursorBy(1)
}

// Remove the character at a specific position
func (te *TextEntry) removeCharAtPos(pos int) {
    if (pos >= 0) && (pos < len(te.value)) {
        te.value = te.value[:pos] + te.value[pos+1:]
    }
}

// Move the cursor
func (te *TextEntry) moveCursorBy(byX int) {
    te.moveCursorTo(te.cursorOffset + byX)
}

func (te *TextEntry) moveCursorTo(toX int) {
    te.cursorOffset = intMinMax(toX, 0, len(te.value))
}