package main

import (
	"regexp"
	"strings"

	"github.com/charmbracelet/lipgloss"
)

// === Цвета подсветки синтаксиса ===
var (
	colorKeyword = lipgloss.NewStyle().Foreground(lipgloss.Color("207")).Bold(true)
	colorString  = lipgloss.NewStyle().Foreground(lipgloss.Color("106"))
	colorComment = lipgloss.NewStyle().Foreground(lipgloss.Color("59")).Italic(true)
	colorNumber  = lipgloss.NewStyle().Foreground(lipgloss.Color("215"))
	colorFunc    = lipgloss.NewStyle().Foreground(lipgloss.Color("81")).Bold(true)
)

// LanguageConfig описывает правила подсветки для одного языка
type LanguageConfig struct {
	Keywords          []string
	LineCommentPrefix string   // "//" или "#" или "--"
	StringDelimiters  []string // `"`, `'`, `` ` ``
	HasNumbers        bool
	CaseInsensitive   bool // для SQL
	VarPrefix         string // для Bash: "$"
}

// languageConfigs — конфиг для каждого языка
var languageConfigs = map[string]LanguageConfig{
	"go": {
		Keywords:          []string{"func", "package", "import", "var", "const", "type", "struct", "interface", "if", "else", "for", "switch", "case", "default", "return", "break", "continue", "defer", "go", "chan", "select", "map", "range", "nil", "true", "false"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`, "`"},
		HasNumbers:        true,
	},
	"py": {
		Keywords:          []string{"def", "class", "if", "else", "elif", "for", "while", "import", "from", "return", "pass", "break", "continue", "lambda", "try", "except", "finally", "with", "as", "True", "False", "None", "and", "or", "not", "in", "is", "raise", "yield", "global", "nonlocal", "del", "assert"},
		LineCommentPrefix: "#",
		StringDelimiters:  []string{`"`, `'`},
		HasNumbers:        true,
	},
	"js": {
		Keywords:          []string{"function", "const", "let", "var", "if", "else", "for", "while", "switch", "case", "default", "return", "break", "continue", "async", "await", "import", "export", "class", "extends", "new", "this", "super", "true", "false", "null", "undefined", "typeof", "instanceof", "void", "delete", "throw", "try", "catch", "finally"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`, `'`, "`"},
		HasNumbers:        true,
	},
	"ts": {
		Keywords:          []string{"function", "const", "let", "var", "if", "else", "for", "while", "switch", "case", "default", "return", "break", "continue", "async", "await", "import", "export", "class", "extends", "new", "this", "super", "true", "false", "null", "undefined", "type", "interface", "enum", "implements", "namespace", "abstract", "readonly", "public", "private", "protected"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`, `'`, "`"},
		HasNumbers:        true,
	},
	"rs": {
		Keywords:          []string{"fn", "let", "mut", "const", "static", "if", "else", "match", "for", "while", "loop", "break", "continue", "return", "pub", "mod", "use", "struct", "enum", "trait", "impl", "unsafe", "async", "await", "move", "ref", "self", "Self", "super", "crate", "true", "false"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`},
		HasNumbers:        true,
	},
	"c": {
		Keywords:          []string{"int", "char", "void", "float", "double", "long", "short", "unsigned", "signed", "if", "else", "for", "while", "do", "switch", "case", "default", "return", "break", "continue", "struct", "union", "enum", "typedef", "static", "const", "extern", "volatile", "sizeof", "NULL"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`},
		HasNumbers:        true,
	},
	"cpp": {
		Keywords:          []string{"int", "char", "void", "float", "double", "long", "short", "unsigned", "signed", "if", "else", "for", "while", "do", "switch", "case", "default", "return", "break", "continue", "struct", "union", "enum", "typedef", "static", "const", "extern", "volatile", "class", "public", "private", "protected", "virtual", "override", "new", "delete", "nullptr", "true", "false", "auto", "template", "typename", "namespace", "using", "this"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`},
		HasNumbers:        true,
	},
	"java": {
		Keywords:          []string{"class", "interface", "extends", "implements", "public", "private", "protected", "static", "final", "void", "int", "boolean", "char", "double", "float", "long", "short", "byte", "if", "else", "for", "while", "do", "switch", "case", "default", "return", "break", "continue", "new", "this", "super", "null", "true", "false", "try", "catch", "finally", "throw", "throws", "import", "package", "abstract", "synchronized"},
		LineCommentPrefix: "//",
		StringDelimiters:  []string{`"`},
		HasNumbers:        true,
	},
	"sql": {
		Keywords:          []string{"SELECT", "FROM", "WHERE", "INSERT", "INTO", "VALUES", "UPDATE", "SET", "DELETE", "CREATE", "TABLE", "DROP", "ALTER", "ADD", "COLUMN", "INDEX", "JOIN", "LEFT", "RIGHT", "INNER", "OUTER", "ON", "AND", "OR", "NOT", "IN", "LIKE", "BETWEEN", "ORDER", "BY", "GROUP", "HAVING", "LIMIT", "OFFSET", "AS", "DISTINCT", "COUNT", "SUM", "AVG", "MAX", "MIN", "NULL", "IS", "PRIMARY", "KEY", "FOREIGN", "REFERENCES", "CONSTRAINT", "UNIQUE", "DEFAULT"},
		LineCommentPrefix: "--",
		StringDelimiters:  []string{`'`},
		HasNumbers:        true,
		CaseInsensitive:   true,
	},
	"sh": {
		Keywords:          []string{"if", "then", "else", "elif", "fi", "for", "do", "done", "while", "case", "esac", "function", "return", "export", "local", "readonly", "unset", "shift", "echo", "exit", "break", "continue", "true", "false"},
		LineCommentPrefix: "#",
		StringDelimiters:  []string{`"`, `'`},
		HasNumbers:        false,
		VarPrefix:         "$",
	},
}

// HighlightLine подсвечивает одну строку кода для заданного типа файла
func HighlightLine(line, fileType string) string {
	cfg, ok := languageConfigs[fileType]
	if !ok {
		return line
	}
	return highlightWithConfig(line, cfg)
}

// highlightWithConfig применяет правила подсветки из LanguageConfig
func highlightWithConfig(line string, cfg LanguageConfig) string {
	result := line

	// 1. Комментарии — применяем первыми, остальное внутри комментария не трогаем
	if cfg.LineCommentPrefix != "" {
		if idx := strings.Index(result, cfg.LineCommentPrefix); idx != -1 {
			before := result[:idx]
			comment := result[idx:]
			result = highlightTokens(before, cfg) + colorComment.Render(comment)
			return result
		}
	}

	result = highlightTokens(result, cfg)
	return result
}

// highlightTokens применяет подсветку строк, ключевых слов, чисел, переменных
func highlightTokens(text string, cfg LanguageConfig) string {
	result := text

	// Строки — выделяем до ключевых слов, чтобы не подсвечивать kw внутри строк
	for _, delim := range cfg.StringDelimiters {
		if delim == "`" {
			result = regexp.MustCompile("`[^`]*`").ReplaceAllStringFunc(result, func(s string) string {
				return colorString.Render(s)
			})
		} else if delim == `"` {
			result = regexp.MustCompile(`"[^"]*"`).ReplaceAllStringFunc(result, func(s string) string {
				return colorString.Render(s)
			})
		} else if delim == `'` {
			result = regexp.MustCompile(`'[^']*'`).ReplaceAllStringFunc(result, func(s string) string {
				return colorString.Render(s)
			})
		}
	}

	// Ключевые слова
	for _, kw := range cfg.Keywords {
		var pattern *regexp.Regexp
		if cfg.CaseInsensitive {
			pattern = regexp.MustCompile(`(?i)\b` + regexp.QuoteMeta(kw) + `\b`)
		} else {
			pattern = regexp.MustCompile(`\b` + regexp.QuoteMeta(kw) + `\b`)
		}
		rendered := colorKeyword.Render(kw)
		if cfg.CaseInsensitive {
			rendered = colorKeyword.Render(strings.ToUpper(kw))
		}
		result = pattern.ReplaceAllString(result, rendered)
	}

	// Числа
	if cfg.HasNumbers {
		result = regexp.MustCompile(`\b\d+(\.\d+)?\b`).ReplaceAllStringFunc(result, func(s string) string {
			return colorNumber.Render(s)
		})
	}

	// Переменные (Bash: $VAR)
	if cfg.VarPrefix != "" {
		escaped := regexp.QuoteMeta(cfg.VarPrefix)
		result = regexp.MustCompile(escaped+`\w+`).ReplaceAllStringFunc(result, func(s string) string {
			return colorFunc.Render(s)
		})
	}

	return result
}