package tui

import (
    "charm.land/lipgloss/v2"
)

// PanelResizer manages the side panel resizing state.
type PanelResizer struct {
    isResizing    bool
    resizeStartX  int
    originalWidth int
    minWidth      int
    maxWidth      int
    isDark        bool
    styles        ResizeStyles
}

// ResizeStyles holds styling for resize indicators.
type ResizeStyles struct {
    Handle       lipgloss.Style
    HandleActive lipgloss.Style
}

// DefaultResizeStyles returns default styles.
func DefaultResizeStyles(isDark bool) ResizeStyles {
    if isDark {
        return ResizeStyles{
            Handle:       lipgloss.NewStyle().Foreground(lipgloss.Color("#4c566a")),
            HandleActive: lipgloss.NewStyle().Foreground(lipgloss.Color("#88c0d0")),
        }
    }
    return ResizeStyles{
        Handle:       lipgloss.NewStyle().Foreground(lipgloss.Color("#9ca0a8")),
        HandleActive: lipgloss.NewStyle().Foreground(lipgloss.Color("#4f8f8f")),
    }
}

// NewPanelResizer creates a new panel resizer.
func NewPanelResizer(minWidth, maxWidth int, isDark bool) *PanelResizer {
    return &PanelResizer{
        isResizing:    false,
        resizeStartX:  0,
        originalWidth: 30,
        minWidth:      minWidth,
        maxWidth:      maxWidth,
        isDark:        isDark,
        styles:        DefaultResizeStyles(isDark),
    }
}

// SetDark updates theme.
func (pr *PanelResizer) SetDark(isDark bool) {
    pr.isDark = isDark
    pr.styles = DefaultResizeStyles(isDark)
}

// StartResize begins a resize operation.
func (pr *PanelResizer) StartResize(x int, currentWidth int) {
    pr.isResizing = true
    pr.resizeStartX = x
    pr.originalWidth = currentWidth
}

// UpdateResize updates the panel width based on mouse movement.
func (pr *PanelResizer) UpdateResize(x int) int {
    if !pr.isResizing {
        return pr.originalWidth
    }

    delta := x - pr.resizeStartX
    newWidth := pr.originalWidth + delta

    // Clamp to min/max
    if newWidth < pr.minWidth {
        newWidth = pr.minWidth
    }
    if newWidth > pr.maxWidth {
        newWidth = pr.maxWidth
    }

    return newWidth
}

// EndResize ends the resize operation.
func (pr *PanelResizer) EndResize() {
    pr.isResizing = false
}

// IsResizing returns true if currently resizing.
func (pr *PanelResizer) IsResizing() bool {
    return pr.isResizing
}

// RenderHandle returns the resize handle visual.
func (pr *PanelResizer) RenderHandle(height int, isActive bool) string {
    style := pr.styles.Handle
    if isActive || pr.isResizing {
        style = pr.styles.HandleActive
    }

    // Create a vertical bar with grip dots
    var b string
    for i := 0; i < height; i++ {
        if i%2 == 0 {
            b += style.Render("│")
        } else {
            b += pr.styles.Handle.Render("│")
        }
    }
    return b
}

// CanResizeAt checks if x is within the resize zone (3 characters from divider).
func (pr *PanelResizer) CanResizeAt(x, dividerX int) bool {
    // Resize zone is 3 chars to the left of the divider
    return x >= dividerX-3 && x <= dividerX
}