package textobject

import (
	"fmt"
	"slices"

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

// Map opposite char
var DirectionalDelimiterMap map[rune]rune = map[rune]rune{
	'(': ')',
	'[': ']',
	'{': '}',
	'<': '>',
}

var singleDelimiterList []rune = []rune{'"', '\'', '`'}

func getStartDelimiterFromEnd(d rune) (rune, bool) {
	if slices.Contains(singleDelimiterList, d) {
		return d, true
	}

	for start, end := range DirectionalDelimiterMap {
		if end == d {
			return start, true
		}
	}

	return ' ', false
}

func getEndDelimiterFromStart(d rune) (rune, bool) {
	if slices.Contains(singleDelimiterList, d) {
		return d, true
	}

	end, found := DirectionalDelimiterMap[d]
	return end, found
}

// Delimiter implements text object for words (iw/aw)
type Delimiter struct {
	Char rune
}

func (to Delimiter) GetRange(m action.Model, cursor core.Position, modifier string) (core.Position, core.Position, core.MotionType) {
	buf := m.ActiveBuffer()

	// Determine which is a starting delimiter and which ends
	_, isStartingDelimiter := DirectionalDelimiterMap[to.Char]
	var (
		startDelim rune
		endDelim   rune
		startFound bool = true
		endFound   bool = true
	)

	if isStartingDelimiter {
		startDelim = to.Char
		endDelim, endFound = getEndDelimiterFromStart(to.Char)
	} else {
		endDelim = to.Char
		startDelim, startFound = getStartDelimiterFromEnd(to.Char)
	}

	if !endFound || !startFound {
		m.SetCommandOutput(&core.CommandOutput{
			Lines:   []string{fmt.Sprintf("Could not find delimiters from '%c'", to.Char)},
			Inline:  true,
			IsError: false,
		})
		return cursor, cursor, core.CharwiseExclusive
	}

	// Convert buffer lines to strings for delimiter finding
	var lines []string
	for i := 0; i < buf.LineCount(); i++ {
		lines = append(lines, buf.Line(i))
	}

	// Use multi-line delimiter pair finding
	start, end, found := findMultiLineDelimiterPair(lines, startDelim, endDelim, cursor, modifier == "a")

	if !found {
		return cursor, cursor, core.CharwiseExclusive
	}

	// Check if positions are valid
	if start.Line > end.Line || (start.Line == end.Line && start.Col > end.Col) {
		return cursor, cursor, core.CharwiseExclusive
	}

	return start, end, core.CharwiseInclusive
}

func findDelimiterStart(line string, delimiter rune, col int, includeDelimiter bool) (core.Position, bool) {
	for i := col; i >= 0; i-- {
		if rune(line[i]) == delimiter {
			if includeDelimiter {
				return core.Position{Line: 0, Col: i}, true
			}
			return core.Position{Line: 0, Col: i + 1}, true
		}
	}
	return core.Position{Line: 0, Col: 0}, false
}

func findDelimiterEnd(line string, delimiter rune, col int, includeDelimiter bool) (core.Position, bool) {
	for i := col; i < len(line); i++ {
		if rune(line[i]) == delimiter {
			if includeDelimiter {
				return core.Position{Line: 0, Col: i}, true
			}
			return core.Position{Line: 0, Col: i - 1}, true
		}
	}
	return core.Position{Line: 0, Col: 0}, false
}

// findDelimiterPair tries to find a matching pair of delimiters.
// First it tries to find delimiters around the cursor.
// If that fails, it searches forward for the next pair.
func findDelimiterPair(line string, startDelim, endDelim rune, cursorCol int, includeDelimiters bool) (core.Position, core.Position, bool) {
	// First, try to find delimiters around cursor
	start, sOk := findDelimiterStart(line, startDelim, cursorCol, includeDelimiters)
	end, eOk := findDelimiterEnd(line, endDelim, cursorCol, includeDelimiters)

	if sOk && eOk {
		// Verify this is actually a valid pair by checking there are no
		// unmatched delimiters between start and end
		var startDelimPos, endDelimPos int
		if includeDelimiters {
			startDelimPos = start.Col
			endDelimPos = end.Col
		} else {
			startDelimPos = start.Col - 1
			endDelimPos = end.Col + 1
		}

		// For proper pair validation, check if this is the nearest matching pair
		// by ensuring the end delimiter we found is the first one after the start
		if isValidPair(line, startDelim, endDelim, startDelimPos, endDelimPos) {
			// Cursor should be at or between the delimiters
			if startDelimPos <= cursorCol && cursorCol <= endDelimPos {
				return start, end, true
			}
		}
	}

	// Not inside delimiters, search forward for next pair
	startDelimPos, foundStart := findNextDelimiter(line, startDelim, cursorCol)
	if !foundStart {
		return core.Position{}, core.Position{}, false
	}

	endDelimPos, foundEnd := findNextDelimiter(line, endDelim, startDelimPos+1)
	if !foundEnd {
		return core.Position{}, core.Position{}, false
	}

	// Validate this pair as well
	if !isValidPair(line, startDelim, endDelim, startDelimPos, endDelimPos) {
		return core.Position{}, core.Position{}, false
	}

	// Calculate start and end positions based on modifier
	if includeDelimiters {
		start = core.Position{Line: 0, Col: startDelimPos}
		end = core.Position{Line: 0, Col: endDelimPos}
	} else {
		start = core.Position{Line: 0, Col: startDelimPos + 1}
		end = core.Position{Line: 0, Col: endDelimPos - 1}
	}

	return start, end, true
}

// isValidPair checks if the delimiters at startPos and endPos form a valid matching pair.
// For same-delimiter pairs (quotes), it checks they form an opening/closing pair.
// For directional pairs (parens, brackets), it ensures the end is the matching closer for the start.
func isValidPair(line string, startDelim, endDelim rune, startPos, endPos int) bool {
	if startPos >= endPos {
		return false
	}

	// For quote-like delimiters where start and end are the same
	if startDelim == endDelim {
		// For quotes, we need to determine if startPos is an opening quote and endPos is a closing quote
		// We do this by counting quotes before each position
		// An opening quote has an even number of quotes before it (0, 2, 4, ...)
		// A closing quote has an odd number of quotes before it (1, 3, 5, ...)

		quotesBeforeStart := 0
		for i := range startPos {
			if rune(line[i]) == startDelim {
				quotesBeforeStart++
			}
		}

		quotesBeforeEnd := quotesBeforeStart + 1 // We know there's at least the startPos quote
		for i := startPos + 1; i < endPos; i++ {
			if rune(line[i]) == startDelim {
				quotesBeforeEnd++
			}
		}

		// startPos should be an opening quote (even number before it)
		// endPos should be a closing quote (odd number before it)
		// AND there should be no quotes between them for a simple pair
		startIsOpening := quotesBeforeStart%2 == 0
		endIsClosing := quotesBeforeEnd%2 == 1
		noQuotesBetween := quotesBeforeEnd == quotesBeforeStart+1

		return startIsOpening && endIsClosing && noQuotesBetween
	}

	// For directional delimiters, check that endPos has the first unmatched closing delimiter
	// Simple approach: ensure there's no end delimiter between startPos and endPos that would
	// close an earlier start delimiter
	nestLevel := 0
	for i := startPos + 1; i < endPos; i++ {
		if rune(line[i]) == startDelim {
			nestLevel++
		} else if rune(line[i]) == endDelim {
			if nestLevel > 0 {
				nestLevel--
			} else {
				// Found an unmatched end delimiter before our endPos
				return false
			}
		}
	}

	// The endPos should close the startPos
	return nestLevel == 0
}

// findNextDelimiter searches forward from startCol for the next occurrence of delimiter
func findNextDelimiter(line string, delimiter rune, startCol int) (int, bool) {
	for i := startCol; i < len(line); i++ {
		if rune(line[i]) == delimiter {
			return i, true
		}
	}
	return 0, false
}

// ============================================================================
// Multi-line Delimiter Functions
// ============================================================================

// findMultiLineDelimiterPair finds a matching pair of delimiters across multiple lines.
// It handles proper nesting for directional delimiters (parens, brackets, braces).
func findMultiLineDelimiterPair(lines []string, startDelim, endDelim rune, cursor core.Position, includeDelimiters bool) (core.Position, core.Position, bool) {
	// First, try to find delimiters around the cursor position (innermost pair)
	start, end, found := findEnclosingDelimiterPair(lines, startDelim, endDelim, cursor, includeDelimiters)
	if found {
		return start, end, true
	}

	// Not inside delimiters, search forward for the next pair
	start, end, found = findNextDelimiterPair(lines, startDelim, endDelim, cursor, includeDelimiters)
	return start, end, found
}

// findEnclosingDelimiterPair finds the innermost delimiter pair that encloses the cursor.
func findEnclosingDelimiterPair(lines []string, startDelim, endDelim rune, cursor core.Position, includeDelimiters bool) (core.Position, core.Position, bool) {
	// Search backward from cursor to find opening delimiter
	startPos, foundStart := searchBackwardForDelimiter(lines, startDelim, endDelim, cursor)
	if !foundStart {
		return core.Position{}, core.Position{}, false
	}

	// Search forward from the opening delimiter to find matching closing delimiter
	endPos, foundEnd := searchForwardForMatchingDelimiter(lines, startDelim, endDelim, startPos)
	if !foundEnd {
		return core.Position{}, core.Position{}, false
	}

	// Check if cursor is between these delimiters
	if !isCursorBetween(cursor, startPos, endPos) {
		return core.Position{}, core.Position{}, false
	}

	// Adjust positions based on includeDelimiters
	start, end, ok := adjustDelimiterPositions(lines, startPos, endPos, includeDelimiters)
	return start, end, ok
}

// findNextDelimiterPair searches forward from cursor for the next delimiter pair.
func findNextDelimiterPair(lines []string, startDelim, endDelim rune, cursor core.Position, includeDelimiters bool) (core.Position, core.Position, bool) {
	// Search forward from cursor for opening delimiter
	startPos, foundStart := searchForwardSimple(lines, startDelim, cursor)
	if !foundStart {
		return core.Position{}, core.Position{}, false
	}

	// Search forward from opening for matching closing delimiter
	endPos, foundEnd := searchForwardForMatchingDelimiter(lines, startDelim, endDelim, startPos)
	if !foundEnd {
		return core.Position{}, core.Position{}, false
	}

	// Adjust positions based on includeDelimiters
	start, end, ok := adjustDelimiterPositions(lines, startPos, endPos, includeDelimiters)
	return start, end, ok
}

// searchBackwardForDelimiter searches backward from cursor to find the nearest opening delimiter
// that could enclose the cursor position.
func searchBackwardForDelimiter(lines []string, startDelim, endDelim rune, cursor core.Position) (core.Position, bool) {
	// For quote-like delimiters, only search current line
	if startDelim == endDelim {
		return searchBackwardForDelimiterSingleLine(lines[cursor.Line], startDelim, endDelim, cursor.Col, cursor.Line)
	}

	// Start from cursor position and go backward
	line := cursor.Line
	col := cursor.Col

	// Search current line from cursor backwards
	for i := col; i >= 0; i-- {
		if i < len(lines[line]) && rune(lines[line][i]) == startDelim {
			// Found a potential start delimiter, verify it could enclose cursor
			pos := core.Position{Line: line, Col: i}
			// Check if this delimiter's matching pair is after the cursor
			endPos, found := searchForwardForMatchingDelimiter(lines, startDelim, endDelim, pos)
			if found && isCursorBetween(cursor, pos, endPos) {
				return pos, true
			}
		}
	}

	// Search previous lines
	for line = cursor.Line - 1; line >= 0; line-- {
		for i := len(lines[line]) - 1; i >= 0; i-- {
			if rune(lines[line][i]) == startDelim {
				pos := core.Position{Line: line, Col: i}
				endPos, found := searchForwardForMatchingDelimiter(lines, startDelim, endDelim, pos)
				if found && isCursorBetween(cursor, pos, endPos) {
					return pos, true
				}
			}
		}
	}

	return core.Position{}, false
}

// searchBackwardForDelimiterSingleLine searches backward on a single line (for quotes).
func searchBackwardForDelimiterSingleLine(line string, startDelim, endDelim rune, col int, lineNum int) (core.Position, bool) {
	for i := col; i >= 0; i-- {
		if i < len(line) && rune(line[i]) == startDelim {
			// For quotes, verify it's an opening quote by checking if it has a matching closing quote
			// Count quotes before this position
			quotesBefore := 0
			for j := 0; j < i; j++ {
				if rune(line[j]) == startDelim {
					quotesBefore++
				}
			}
			// If even number of quotes before, this is an opening quote
			if quotesBefore%2 == 0 {
				// Find matching closing quote
				for j := i + 1; j < len(line); j++ {
					if rune(line[j]) == endDelim {
						// Check if cursor is between i and j
						if col > i && col < j {
							return core.Position{Line: lineNum, Col: i}, true
						}
						break
					}
				}
			}
		}
	}
	return core.Position{}, false
}

// searchForwardForMatchingDelimiter searches forward from startPos to find the matching closing delimiter.
// It properly handles nesting for directional delimiters.
func searchForwardForMatchingDelimiter(lines []string, startDelim, endDelim rune, startPos core.Position) (core.Position, bool) {
	nestLevel := 0
	line := startPos.Line
	startCol := startPos.Col + 1 // Start after the opening delimiter

	// For quote-like delimiters (same start and end)
	if startDelim == endDelim {
		// Simple search for next occurrence on same line
		if line < len(lines) {
			for i := startCol; i < len(lines[line]); i++ {
				if rune(lines[line][i]) == endDelim {
					return core.Position{Line: line, Col: i}, true
				}
			}
		}
		return core.Position{}, false
	}

	// For directional delimiters with nesting
	// Search current line from startCol
	for i := startCol; i < len(lines[line]); i++ {
		ch := rune(lines[line][i])
		if ch == startDelim {
			nestLevel++
		} else if ch == endDelim {
			if nestLevel == 0 {
				return core.Position{Line: line, Col: i}, true
			}
			nestLevel--
		}
	}

	// Search subsequent lines
	for line = startPos.Line + 1; line < len(lines); line++ {
		for i := 0; i < len(lines[line]); i++ {
			ch := rune(lines[line][i])
			if ch == startDelim {
				nestLevel++
			} else if ch == endDelim {
				if nestLevel == 0 {
					return core.Position{Line: line, Col: i}, true
				}
				nestLevel--
			}
		}
	}

	return core.Position{}, false
}

// searchForwardSimple searches forward from cursor for the next occurrence of delimiter.
func searchForwardSimple(lines []string, delimiter rune, cursor core.Position) (core.Position, bool) {
	// Search current line from cursor
	for i := cursor.Col; i < len(lines[cursor.Line]); i++ {
		if rune(lines[cursor.Line][i]) == delimiter {
			return core.Position{Line: cursor.Line, Col: i}, true
		}
	}

	// Search subsequent lines
	for line := cursor.Line + 1; line < len(lines); line++ {
		for i := 0; i < len(lines[line]); i++ {
			if rune(lines[line][i]) == delimiter {
				return core.Position{Line: line, Col: i}, true
			}
		}
	}

	return core.Position{}, false
}

// isCursorBetween checks if cursor is between start and end positions.
func isCursorBetween(cursor, start, end core.Position) bool {
	// Check if cursor is after or at start
	if cursor.Line < start.Line || (cursor.Line == start.Line && cursor.Col < start.Col) {
		return false
	}

	// Check if cursor is before or at end
	if cursor.Line > end.Line || (cursor.Line == end.Line && cursor.Col > end.Col) {
		return false
	}

	return true
}

// hasOnlyWhitespaceBefore checks if there is only whitespace before the character at col.
func hasOnlyWhitespaceBefore(line string, col int) bool {
	for i := range col {
		if !isWhitespace(rune(line[i])) {
			return false
		}
	}
	return true
}

// isWhitespace checks if a rune is whitespace.
func isWhitespace(r rune) bool {
	return r == ' ' || r == '\t'
}

// adjustDelimiterPositions adjusts the delimiter positions based on whether to include delimiters.
func adjustDelimiterPositions(lines []string, startPos, endPos core.Position, includeDelimiters bool) (core.Position, core.Position, bool) {
	if includeDelimiters {
		// Include the delimiters themselves
		return startPos, endPos, true
	}

	// Exclude the delimiters - start after opening, end before closing
	start := core.Position{Line: startPos.Line, Col: startPos.Col + 1}
	end := core.Position{Line: endPos.Line, Col: endPos.Col - 1}

	// Handle special cases
	if startPos.Line == endPos.Line {
		// Same line - check if there's content between delimiters
		if startPos.Col+1 > endPos.Col-1 {
			// Empty delimiters like "()" - return positions that will be detected as invalid
			return start, end, true
		}
	} else {
		// Multi-line case
		// If start position is beyond the line (delimiter was last char on its line)
		if start.Col >= len(lines[start.Line]) {
			// Position at end of line to include the newline in deletion
			start.Col = len(lines[start.Line])
		}

		// If end position is negative (delimiter was first char on its line) OR
		// delimiter has only whitespace before it on its line
		if end.Col < 0 || hasOnlyWhitespaceBefore(lines[endPos.Line], endPos.Col) {
			// Position at end of previous line to include that line's newline
			if end.Line > 0 {
				end.Line--
				end.Col = len(lines[end.Line])
			}
		}
	}

	return start, end, true
}