package editor

import (
	"fmt"
	"strings"

	"git.gophernest.net/azpect/TextEditor/internal/core"
	"git.gophernest.net/azpect/TextEditor/internal/style"
)

// Model.View: Renders the complete editor view including buffer content, line
// numbers, status bar, and command line.
func (m Model) View() string {
	win := m.ActiveWindow()

	// NOTES:
	// One single command line across entire viewport
	// Each window has its own line numbers and gutter
	// Each window has its own status bar and mode

	styles := m.Styles()
	settings := m.Settings()

	// Draw window
	view := viewWindow(win, styles, settings, m.Mode())

	// Command bar is seperate
	cmdBar := drawCommandBar(m)

	return view + cmdBar

	// view.WriteString(drawStatusBar(m))
	// view.WriteString("\n")
	// view.WriteString(drawCommandBar(m))
	//
	// return view.String()
}

// viewWindow: Renders a single window's content including line numbers and buffer text.
// Each window has its own line numbers, gutter, and viewport dimensions.
func viewWindow(w *core.Window, styles style.Styles, settings core.Settings, mode core.Mode) string {
	buf := w.Buffer
	var view strings.Builder

	// Compute window size (y)
	start := w.ScrollY
	end := w.ScrollY + w.ViewportHeight()

	// Draw buffer lines
	for lineNum := start; lineNum < end; lineNum++ {
		if lineNum < buf.LineCount() {
			line := drawLine(w, styles, settings, mode, buf.Line(lineNum), lineNum)
			view.WriteString(line)
		}
		view.WriteRune('\n')
	}

	// Draw status line
	statusBar := drawStatusBar(w, mode)
	view.WriteString(statusBar + "\n")

	return view.String()
}

// drawLine: Renders a single line with syntax highlighting, cursor, and visual selection.
// Handles gutter, cursor rendering, and visual mode highlighting.
func drawLine(w *core.Window, styles style.Styles, settings core.Settings, mode core.Mode, line string, lineNumber int) string {
	runes := []rune(line)

	curStyle := styles.CursorStyle(mode)
	visStyle := styles.VisualHighlight

	var view strings.Builder

	// Draw gutter first
	gutter := drawGutter(w, styles, settings, lineNumber)
	view.WriteString(gutter)

	// Now draw the line content
	for col := 0; col <= len(runes); col++ {
		// Current char is cursor
		if col == w.Cursor.Col && lineNumber == w.Cursor.Line {
			if col < len(runes) {
				view.WriteString(curStyle.Render(string(runes[col])))
			} else {
				view.WriteString(curStyle.Render(" "))
			}

			// Not cursor, but not end
		} else if col < len(runes) {
			if mode.IsVisualMode() && posInsideSelection(w, mode, col, lineNumber) {
				view.WriteString(visStyle.Render(string(runes[col])))
			} else {
				view.WriteRune(runes[col])
			}
			// Allow highlight on blank lines or chars
		} else if mode.IsVisualMode() && posInsideSelection(w, mode, col, lineNumber) {
			view.WriteString(visStyle.Render(" "))
		}
	}

	return view.String()
}

// drawGutter: Renders the line number gutter with support for both absolute and
// relative line numbers, highlighting the current line differently.
func drawGutter(w *core.Window, styles style.Styles, settings core.Settings, curLine int) string {
	if !(settings.Number || settings.RelativeNumber) {
		return ""
	}

	// Required vars
	var (
		view        strings.Builder
		gutSize     int  = settings.GutterSize - 1 // -1 is for padding
		currentLine bool = curLine == w.Cursor.Line
		lineNumber  int

		gutter         string
		gutterStyle    = styles.Gutter
		gutterStyleCur = styles.GutterCurrentLine
	)

	// If we have relative setting, set the numbers relatively
	if settings.RelativeNumber {
		if curLine > w.Cursor.Line {
			lineNumber = curLine - w.Cursor.Line
		}

		if curLine < w.Cursor.Line {
			lineNumber = w.Cursor.Line - curLine
		}
	}

	// If we have number setting AND not relative setting OR we are on current line, use current line number
	if (settings.Number && !settings.RelativeNumber) || (settings.Number && currentLine) {
		lineNumber = curLine + 1
	}

	// Draw the gutter
	gutter = fmt.Sprintf("%*d ", gutSize, lineNumber)
	if currentLine {
		view.WriteString(gutterStyleCur.Render(gutter))
	} else {
		view.WriteString(gutterStyle.Render(gutter))
	}

	return view.String()

	// if m.Settings().Number || m.Settings().RelativeNumber {
	// 	var (
	// 		gutter      string
	// 		currentLine bool = false
	// 		lineNumber  int
	// 	)
	//
	// 	if m.Settings().RelativeNumber {
	// 		// Relative line numbers: show distance from cursor, current line shows absolute
	// 		if i > win.Cursor.Line {
	// 			lineNumber = i - win.Cursor.Line
	// 			gutter = fmt.Sprintf("%*d ", m.Settings().GutterSize-1, lineNumber)
	// 		} else if i < win.Cursor.Line {
	// 			lineNumber = win.Cursor.Line - i
	// 			gutter = fmt.Sprintf("%*d ", m.Settings().GutterSize-1, lineNumber)
	// 		} else {
	// 			// Current line: show absolute number if Number is also set, otherwise show 0
	// 			currentLine = true
	// 			if m.Settings().Number {
	// 				lineNumber = i + 1
	// 				gutter = fmt.Sprintf("%*d ", m.Settings().GutterSize-1, lineNumber)
	// 			} else {
	// 				gutter = fmt.Sprintf("%*d ", m.Settings().GutterSize-1, 0)
	// 			}
	// 		}
	// 	} else if m.Settings().Number {
	// 		// Absolute line numbers only
	// 		lineNumber = i + 1
	// 		currentLine = (i == win.Cursor.Line)
	// 		gutter = fmt.Sprintf("%*d ", m.Settings().GutterSize-1, lineNumber)
	// 	}
	// 	if currentLine {
	// 		view.WriteString(m.Styles().GutterCurrentLine.Render(gutter))
	// 	} else {
	// 		view.WriteString(m.Styles().Gutter.Render(gutter))
	// 	}
	// }
}

// drawStatusBar: Renders the status bar with mode and cursor position,
// padding the middle with spaces to fill the terminal width.
func drawStatusBar(w *core.Window, mode core.Mode) string {
	left := leftBar(w, mode)
	right := rightBar(w, mode)

	diff := w.Width - (len(left) + len(right))

	// This happens when the terminal spawns
	if diff <= 0 {
		return ""
	}

	middle := strings.Repeat(" ", diff)
	return left + middle + right
}

// leftBar: Returns the left side of the status bar showing the current mode.
func leftBar(w *core.Window, mode core.Mode) string {
	buf := w.Buffer
	return fmt.Sprintf(" %s  %s", mode.ToString(), buf.Filename)
}

// rightBar: Returns the right side of the status bar showing cursor position
// and selection count in visual mode.
func rightBar(w *core.Window, mode core.Mode) (bar string) {
	if mode.IsVisualMode() {
		lineCount := max(w.Anchor.Line, w.Cursor.Line) - min(w.Anchor.Line, w.Cursor.Line) + 1
		bar = fmt.Sprintf("%d:%d  <%d>", w.Cursor.Line+1, w.Cursor.Col+1, lineCount)
	} else {
		bar = fmt.Sprintf("%d:%d ", w.Cursor.Line+1, w.Cursor.Col+1)
	}
	buf := w.Buffer
	bar = fmt.Sprintf("%s %s", buf.Filetype, bar)
	return
}

// drawCommandBar: Renders the command line showing command input, errors, or
// output depending on the current mode and state.
func drawCommandBar(m Model) string {
	// Compute left bar (command side)
	var leftBar string
	if m.Mode() == core.CommandMode {
		leftBar = ":"
		cmd := m.Command()
		cur := m.CommandCursor()
		for i := 0; i < len(cmd); i++ {
			if i == cur {
				leftBar += m.Styles().CursorStyle(m.Mode()).Render(string(cmd[i]))
			} else {
				leftBar += string(cmd[i])
			}
		}
		// Cursor at end of command
		if cur >= len(cmd) {
			leftBar += m.Styles().CursorStyle(m.Mode()).Render(" ")
		}
		// bar = fmt.Sprintf("%s  %d", bar, cur)
	} else if m.CommandError() != nil {
		leftBar = m.Styles().CommandError.Render(m.CommandError().Error())
	} else if strings.TrimSpace(m.CommandOutput()) != "" {
		leftBar = m.CommandOutput()
	} else if strings.TrimSpace(m.Command()) != "" {
		leftBar = fmt.Sprintf(":%s", m.Command())
	}

	// Compute right bar

	var rightBar string
	if len(m.input.Pending()) > 0 {
		width := 10 // Size of the block to display
		rightBar = fmt.Sprintf("%-*s", width, m.input.Pending())
	}

	dif := m.termWidth - (len(leftBar) + len(rightBar))

	bar := leftBar + strings.Repeat(" ", dif) + rightBar
	return bar
}

// posInsideSelection: Returns true if the given position is inside the current
// visual selection, handling all three visual modes differently.
func posInsideSelection(w *core.Window, mode core.Mode, col, line int) bool {
	switch mode {
	case core.VisualLineMode:
		startY := min(w.Anchor.Line, w.Cursor.Line)
		endY := max(w.Anchor.Line, w.Cursor.Line)
		return line >= startY && line <= endY

	case core.VisualMode:
		ax := w.Anchor.Col
		ay := w.Anchor.Line

		cx := w.Cursor.Col
		cy := w.Cursor.Line

		// Normalize so start is always before end in document order
		var startX, startY, endX, endY int
		if ay < cy || (ay == cy && ax <= cx) {
			startX, startY = ax, ay
			endX, endY = cx, cy
		} else {
			startX, startY = cx, cy
			endX, endY = ax, ay
		}

		// Position is inside if it falls within [start, end] inclusive
		afterStart := line > startY || (line == startY && col >= startX)
		beforeEnd := line < endY || (line == endY && col <= endX)
		return afterStart && beforeEnd

	case core.VisualBlockMode:
		startX := min(w.Anchor.Col, w.Cursor.Col)
		startY := min(w.Anchor.Line, w.Cursor.Line)
		endX := max(w.Anchor.Col, w.Cursor.Col)
		endY := max(w.Anchor.Line, w.Cursor.Line)

		return col >= startX && col <= endX &&
			line >= startY && line <= endY

	default:
		return false
	}
}