package drizzle

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"git.warky.dev/wdevs/relspecgo/pkg/models"
	"git.warky.dev/wdevs/relspecgo/pkg/writers"
)

// Writer implements the writers.Writer interface for Drizzle ORM
type Writer struct {
	options    *writers.WriterOptions
	typeMapper *TypeMapper
	templates  *Templates
}

// NewWriter creates a new Drizzle writer with the given options
func NewWriter(options *writers.WriterOptions) *Writer {
	w := &Writer{
		options:    options,
		typeMapper: NewTypeMapper(),
	}

	// Initialize templates
	tmpl, err := NewTemplates()
	if err != nil {
		// Should not happen with embedded templates
		panic(fmt.Sprintf("failed to initialize templates: %v", err))
	}
	w.templates = tmpl

	return w
}

// WriteDatabase writes a complete database as Drizzle schema
func (w *Writer) WriteDatabase(db *models.Database) error {
	// Check if multi-file mode is enabled
	multiFile := w.shouldUseMultiFile()

	if multiFile {
		return w.writeMultiFile(db)
	}

	return w.writeSingleFile(db)
}

// WriteSchema writes a schema as Drizzle schema
func (w *Writer) WriteSchema(schema *models.Schema) error {
	// Create a temporary database with just this schema
	db := models.InitDatabase(schema.Name)
	db.Schemas = []*models.Schema{schema}

	return w.WriteDatabase(db)
}

// WriteTable writes a single table as a Drizzle schema
func (w *Writer) WriteTable(table *models.Table) error {
	// Create a temporary schema and database
	schema := models.InitSchema(table.Schema)
	schema.Tables = []*models.Table{table}

	db := models.InitDatabase(schema.Name)
	db.Schemas = []*models.Schema{schema}

	return w.WriteDatabase(db)
}

// writeSingleFile writes all tables to a single file
func (w *Writer) writeSingleFile(db *models.Database) error {
	templateData := NewTemplateData()

	// Build enum map for quick lookup
	enumMap := w.buildEnumMap(db)

	// Process all schemas
	for _, schema := range db.Schemas {
		// Add enums
		for _, enum := range schema.Enums {
			enumData := NewEnumData(enum, w.typeMapper)
			templateData.AddEnum(enumData)
		}

		// Add tables
		for _, table := range schema.Tables {
			tableData := w.buildTableData(table, schema, db, enumMap)
			templateData.AddTable(tableData)
		}
	}

	// Add imports
	w.addImports(templateData, db)

	// Finalize imports
	templateData.FinalizeImports()

	// Generate code
	code, err := w.templates.GenerateCode(templateData)
	if err != nil {
		return fmt.Errorf("failed to generate code: %w", err)
	}

	// Write output
	return w.writeOutput(code)
}

// writeMultiFile writes each table to a separate file
func (w *Writer) writeMultiFile(db *models.Database) error {
	// Ensure output path is a directory
	if w.options.OutputPath == "" {
		return fmt.Errorf("output path is required for multi-file mode")
	}

	// Create output directory if it doesn't exist
	if err := os.MkdirAll(w.options.OutputPath, 0755); err != nil {
		return fmt.Errorf("failed to create output directory: %w", err)
	}

	// Build enum map for quick lookup
	enumMap := w.buildEnumMap(db)

	// Process all schemas
	for _, schema := range db.Schemas {
		// Write enums file if there are any
		if len(schema.Enums) > 0 {
			if err := w.writeEnumsFile(schema); err != nil {
				return err
			}
		}

		// Write each table to a separate file
		for _, table := range schema.Tables {
			if err := w.writeTableFile(table, schema, db, enumMap); err != nil {
				return err
			}
		}
	}

	return nil
}

// writeEnumsFile writes all enums to a separate file
func (w *Writer) writeEnumsFile(schema *models.Schema) error {
	templateData := NewTemplateData()

	// Add enums
	for _, enum := range schema.Enums {
		enumData := NewEnumData(enum, w.typeMapper)
		templateData.AddEnum(enumData)
	}

	// Add imports for enums
	templateData.AddImport("import { pgEnum } from 'drizzle-orm/pg-core';")

	// Generate code
	code, err := w.templates.GenerateCode(templateData)
	if err != nil {
		return fmt.Errorf("failed to generate enums code: %w", err)
	}

	// Write to enums.ts file
	filename := filepath.Join(w.options.OutputPath, "enums.ts")
	return os.WriteFile(filename, []byte(code), 0644)
}

// writeTableFile writes a single table to its own file
func (w *Writer) writeTableFile(table *models.Table, schema *models.Schema, db *models.Database, enumMap map[string]bool) error {
	templateData := NewTemplateData()

	// Build table data
	tableData := w.buildTableData(table, schema, db, enumMap)
	templateData.AddTable(tableData)

	// Add imports
	w.addImports(templateData, db)

	// If there are enums, add import from enums file
	if len(schema.Enums) > 0 && w.tableUsesEnum(table, enumMap) {
		// Import enum definitions from enums.ts
		enumNames := w.getTableEnumNames(table, schema, enumMap)
		if len(enumNames) > 0 {
			importLine := fmt.Sprintf("import { %s } from './enums';", strings.Join(enumNames, ", "))
			templateData.AddImport(importLine)
		}
	}

	// Finalize imports
	templateData.FinalizeImports()

	// Generate code
	code, err := w.templates.GenerateCode(templateData)
	if err != nil {
		return fmt.Errorf("failed to generate code for table %s: %w", table.Name, err)
	}

	// Generate filename: {tableName}.ts
	// Sanitize table name to remove quotes, comments, and invalid characters
	safeTableName := writers.SanitizeFilename(table.Name)
	filename := filepath.Join(w.options.OutputPath, safeTableName+".ts")
	return os.WriteFile(filename, []byte(code), 0644)
}

// buildTableData builds TableData from a models.Table
func (w *Writer) buildTableData(table *models.Table, schema *models.Schema, db *models.Database, enumMap map[string]bool) *TableData {
	tableData := NewTableData(table, w.typeMapper)

	// Add columns
	for _, colName := range w.getSortedColumnNames(table) {
		col := table.Columns[colName]

		// Check if this column uses an enum
		isEnum := enumMap[col.Type]

		columnData := NewColumnData(col, table, w.typeMapper, isEnum)

		// Set TypeScript type
		drizzleType := w.typeMapper.SQLTypeToDrizzle(col.Type)
		enumName := ""
		if isEnum {
			// For enums, use the enum type name
			enumName = col.Type
		}
		baseType := w.typeMapper.DrizzleTypeToTypeScript(drizzleType, isEnum, enumName)

		// Add null union if column is nullable
		if !col.NotNull && !col.IsPrimaryKey {
			columnData.TypeScriptType = baseType + " | null"
		} else {
			columnData.TypeScriptType = baseType
		}

		// Check if this column is a foreign key
		if fk := w.getForeignKeyForColumn(col.Name, table); fk != nil {
			columnData.IsForeignKey = true
			refTableName := fk.ReferencedTable
			refChain := w.typeMapper.BuildReferencesChain(fk, refTableName)
			if refChain != "" {
				columnData.ReferencesLine = "." + refChain
				// Append to the drizzle chain
				columnData.DrizzleChain += columnData.ReferencesLine
			}
		}

		tableData.AddColumn(columnData)
	}

	// Collect all column field names that are used in indexes
	indexColumnFields := make(map[string]bool)

	// Add indexes (excluding single-column unique indexes, which are handled inline)
	for _, index := range table.Indexes {
		// Skip single-column unique indexes (handled by .unique() modifier)
		if index.Unique && len(index.Columns) == 1 {
			continue
		}

		// Track which columns are used in indexes
		for _, colName := range index.Columns {
			// Find the field name for this column
			if col, exists := table.Columns[colName]; exists {
				fieldName := w.typeMapper.ToCamelCase(col.Name)
				indexColumnFields[fieldName] = true
			}
		}

		indexData := NewIndexData(index, tableData.Name, w.typeMapper)
		tableData.AddIndex(indexData)
	}

	// Add multi-column unique constraints as unique indexes
	for _, constraint := range table.Constraints {
		if constraint.Type == models.UniqueConstraint && len(constraint.Columns) > 1 {
			// Create a unique index for this constraint
			indexData := &IndexData{
				Name:     w.typeMapper.ToCamelCase(constraint.Name) + "Idx",
				Columns:  constraint.Columns,
				IsUnique: true,
			}

			// Track which columns are used in indexes
			for _, colName := range constraint.Columns {
				if col, exists := table.Columns[colName]; exists {
					fieldName := w.typeMapper.ToCamelCase(col.Name)
					indexColumnFields[fieldName] = true
				}
			}

			// Build column references as field names (for destructuring)
			colRefs := make([]string, len(constraint.Columns))
			for i, colName := range constraint.Columns {
				if col, exists := table.Columns[colName]; exists {
					colRefs[i] = w.typeMapper.ToCamelCase(col.Name)
				} else {
					colRefs[i] = w.typeMapper.ToCamelCase(colName)
				}
			}

			indexData.Definition = "uniqueIndex('" + constraint.Name + "').on(" + joinStrings(colRefs, ", ") + ")"
			tableData.AddIndex(indexData)
		}
	}

	// Convert index column fields map to sorted slice
	if len(indexColumnFields) > 0 {
		fields := make([]string, 0, len(indexColumnFields))
		for field := range indexColumnFields {
			fields = append(fields, field)
		}
		// Sort for consistent output
		sortStrings(fields)
		tableData.IndexColumnFields = fields
	}

	return tableData
}

// sortStrings sorts a slice of strings in place
func sortStrings(strs []string) {
	for i := 0; i < len(strs); i++ {
		for j := i + 1; j < len(strs); j++ {
			if strs[i] > strs[j] {
				strs[i], strs[j] = strs[j], strs[i]
			}
		}
	}
}

// addImports adds the necessary imports to the template data
func (w *Writer) addImports(templateData *TemplateData, db *models.Database) {
	// Determine which Drizzle imports we need
	needsPgTable := len(templateData.Tables) > 0
	needsPgEnum := len(templateData.Enums) > 0
	needsIndex := false
	needsUniqueIndex := false
	needsSQL := false

	// Check what we need based on tables
	for _, table := range templateData.Tables {
		for _, index := range table.Indexes {
			if index.IsUnique {
				needsUniqueIndex = true
			} else {
				needsIndex = true
			}
		}

		// Check if any column uses SQL default values
		for _, col := range table.Columns {
			if strings.Contains(col.DrizzleChain, "sql`") {
				needsSQL = true
			}
		}
	}

	// Build the import statement
	imports := make([]string, 0)

	if needsPgTable {
		imports = append(imports, "pgTable")
	}
	if needsPgEnum {
		imports = append(imports, "pgEnum")
	}

	// Add column types - for now, add common ones
	// TODO: Could be optimized to only include used types
	columnTypes := []string{
		"integer", "bigint", "smallint",
		"serial", "bigserial", "smallserial",
		"text", "varchar", "char",
		"boolean", "numeric", "real", "doublePrecision",
		"timestamp", "date", "time", "interval",
		"json", "jsonb", "uuid", "bytea",
	}
	imports = append(imports, columnTypes...)

	if needsIndex {
		imports = append(imports, "index")
	}
	if needsUniqueIndex {
		imports = append(imports, "uniqueIndex")
	}

	importLine := "import { " + strings.Join(imports, ", ") + " } from 'drizzle-orm/pg-core';"
	templateData.AddImport(importLine)

	// Add SQL import if needed
	if needsSQL {
		templateData.AddImport("import { sql } from 'drizzle-orm';")
	}
}

// buildEnumMap builds a map of enum type names for quick lookup
func (w *Writer) buildEnumMap(db *models.Database) map[string]bool {
	enumMap := make(map[string]bool)

	for _, schema := range db.Schemas {
		for _, enum := range schema.Enums {
			enumMap[enum.Name] = true
			// Also add lowercase version for case-insensitive lookup
			enumMap[strings.ToLower(enum.Name)] = true
		}
	}

	return enumMap
}

// tableUsesEnum checks if a table uses any enum types
func (w *Writer) tableUsesEnum(table *models.Table, enumMap map[string]bool) bool {
	for _, col := range table.Columns {
		if enumMap[col.Type] || enumMap[strings.ToLower(col.Type)] {
			return true
		}
	}
	return false
}

// getTableEnumNames returns the list of enum variable names used by a table
func (w *Writer) getTableEnumNames(table *models.Table, schema *models.Schema, enumMap map[string]bool) []string {
	enumNames := make([]string, 0)
	seen := make(map[string]bool)

	for _, col := range table.Columns {
		if enumMap[col.Type] || enumMap[strings.ToLower(col.Type)] {
			// Find the enum in schema
			for _, enum := range schema.Enums {
				if strings.EqualFold(enum.Name, col.Type) {
					varName := w.typeMapper.ToCamelCase(enum.Name)
					if !seen[varName] {
						enumNames = append(enumNames, varName)
						seen[varName] = true
					}
					break
				}
			}
		}
	}

	return enumNames
}

// getSortedColumnNames returns column names sorted by sequence or name
func (w *Writer) getSortedColumnNames(table *models.Table) []string {
	// Convert map to slice
	columns := make([]*models.Column, 0, len(table.Columns))
	for _, col := range table.Columns {
		columns = append(columns, col)
	}

	// Sort by sequence, then by primary key, then by name
	// (Similar to GORM writer)
	sortColumns := func(i, j int) bool {
		// Sort by sequence if both have it
		if columns[i].Sequence > 0 && columns[j].Sequence > 0 {
			return columns[i].Sequence < columns[j].Sequence
		}

		// Put primary keys first
		if columns[i].IsPrimaryKey != columns[j].IsPrimaryKey {
			return columns[i].IsPrimaryKey
		}

		// Otherwise sort alphabetically
		return columns[i].Name < columns[j].Name
	}

	// Create a custom sorter
	for i := 0; i < len(columns); i++ {
		for j := i + 1; j < len(columns); j++ {
			if !sortColumns(i, j) {
				columns[i], columns[j] = columns[j], columns[i]
			}
		}
	}

	// Extract names
	names := make([]string, len(columns))
	for i, col := range columns {
		names[i] = col.Name
	}

	return names
}

// getForeignKeyForColumn returns the foreign key constraint for a column, if any
func (w *Writer) getForeignKeyForColumn(columnName string, table *models.Table) *models.Constraint {
	for _, constraint := range table.Constraints {
		if constraint.Type == models.ForeignKeyConstraint {
			for _, col := range constraint.Columns {
				if col == columnName {
					return constraint
				}
			}
		}
	}
	return nil
}

// writeOutput writes the content to file or stdout
func (w *Writer) writeOutput(content string) error {
	if w.options.OutputPath != "" {
		return os.WriteFile(w.options.OutputPath, []byte(content), 0644)
	}

	// Print to stdout
	fmt.Print(content)
	return nil
}

// shouldUseMultiFile determines whether to use multi-file mode based on metadata or output path
func (w *Writer) shouldUseMultiFile() bool {
	// Check if multi_file is explicitly set in metadata
	if w.options.Metadata != nil {
		if mf, ok := w.options.Metadata["multi_file"].(bool); ok {
			return mf
		}
	}

	// Auto-detect based on output path
	if w.options.OutputPath == "" {
		// No output path means stdout (single file)
		return false
	}

	// Check if path ends with .ts (explicit file)
	if strings.HasSuffix(w.options.OutputPath, ".ts") {
		return false
	}

	// Check if path ends with directory separator
	if strings.HasSuffix(w.options.OutputPath, "/") || strings.HasSuffix(w.options.OutputPath, "\\") {
		return true
	}

	// Check if path exists and is a directory
	info, err := os.Stat(w.options.OutputPath)
	if err == nil && info.IsDir() {
		return true
	}

	// Default to single file for ambiguous cases
	return false
}