package template

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"text/template"

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

// EntrypointMode defines how the template is executed
type EntrypointMode string

const (
	// DatabaseMode executes the template once for the entire database (single output)
	DatabaseMode EntrypointMode = "database"
	// SchemaMode executes the template once per schema (multi-file output)
	SchemaMode EntrypointMode = "schema"
	// DomainMode executes the template once per domain (multi-file output)
	DomainMode EntrypointMode = "domain"
	// ScriptMode executes the template once per script (multi-file output)
	ScriptMode EntrypointMode = "script"
	// TableMode executes the template once per table (multi-file output)
	TableMode EntrypointMode = "table"
)

// Writer implements the writers.Writer interface for template-based output
type Writer struct {
	options         *writers.WriterOptions
	templatePath    string
	funcMap         template.FuncMap
	tmpl            *template.Template
	mode            EntrypointMode
	filenamePattern string
}

// NewWriter creates a new template writer with the given options
func NewWriter(options *writers.WriterOptions) (*Writer, error) {
	w := &Writer{
		options:         options,
		funcMap:         BuildFuncMap(),
		mode:            DatabaseMode, // default mode
		filenamePattern: "{{.Name}}.txt",
	}

	// Extract template path from metadata
	if options.Metadata != nil {
		if path, ok := options.Metadata["template_path"].(string); ok {
			w.templatePath = path
		}

		if mode, ok := options.Metadata["mode"].(string); ok {
			w.mode = EntrypointMode(mode)
		}

		if pattern, ok := options.Metadata["filename_pattern"].(string); ok {
			w.filenamePattern = pattern
		}
	}

	// Validate template path
	if w.templatePath == "" {
		return nil, NewTemplateLoadError("template path is required", nil)
	}

	// Load and parse template
	if err := w.loadTemplate(); err != nil {
		return nil, err
	}

	return w, nil
}

// WriteDatabase writes a database using the template
func (w *Writer) WriteDatabase(db *models.Database) error {
	switch w.mode {
	case DatabaseMode:
		return w.executeDatabaseMode(db)
	case SchemaMode:
		return w.executeSchemaMode(db)
	case DomainMode:
		return w.executeDomainMode(db)
	case ScriptMode:
		return w.executeScriptMode(db)
	case TableMode:
		return w.executeTableMode(db)
	default:
		return fmt.Errorf("unknown entrypoint mode: %s", w.mode)
	}
}

// WriteSchema writes a schema using the template
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 using the template
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)
}

// executeDatabaseMode executes the template once for the entire database
func (w *Writer) executeDatabaseMode(db *models.Database) error {
	data := NewDatabaseData(db, w.options.Metadata)
	output, err := w.executeTemplate(data)
	if err != nil {
		return err
	}

	return w.writeOutput(output, w.options.OutputPath)
}

// executeSchemaMode executes the template once per schema
func (w *Writer) executeSchemaMode(db *models.Database) error {
	for _, schema := range db.Schemas {
		data := NewSchemaData(schema, w.options.Metadata)
		output, err := w.executeTemplate(data)
		if err != nil {
			return fmt.Errorf("failed to execute template for schema %s: %w", schema.Name, err)
		}

		filename, err := w.generateFilename(data)
		if err != nil {
			return fmt.Errorf("failed to generate filename for schema %s: %w", schema.Name, err)
		}

		if err := w.writeOutput(output, filename); err != nil {
			return fmt.Errorf("failed to write output for schema %s: %w", schema.Name, err)
		}
	}

	return nil
}

// executeDomainMode executes the template once per domain
func (w *Writer) executeDomainMode(db *models.Database) error {
	for _, domain := range db.Domains {
		data := NewDomainData(domain, db, w.options.Metadata)
		output, err := w.executeTemplate(data)
		if err != nil {
			return fmt.Errorf("failed to execute template for domain %s: %w", domain.Name, err)
		}

		filename, err := w.generateFilename(data)
		if err != nil {
			return fmt.Errorf("failed to generate filename for domain %s: %w", domain.Name, err)
		}

		if err := w.writeOutput(output, filename); err != nil {
			return fmt.Errorf("failed to write output for domain %s: %w", domain.Name, err)
		}
	}

	return nil
}

// executeScriptMode executes the template once per script
func (w *Writer) executeScriptMode(db *models.Database) error {
	for _, schema := range db.Schemas {
		for _, script := range schema.Scripts {
			data := NewScriptData(script, schema, db, w.options.Metadata)
			output, err := w.executeTemplate(data)
			if err != nil {
				return fmt.Errorf("failed to execute template for script %s: %w", script.Name, err)
			}

			filename, err := w.generateFilename(data)
			if err != nil {
				return fmt.Errorf("failed to generate filename for script %s: %w", script.Name, err)
			}

			if err := w.writeOutput(output, filename); err != nil {
				return fmt.Errorf("failed to write output for script %s: %w", script.Name, err)
			}
		}
	}

	return nil
}

// executeTableMode executes the template once per table
func (w *Writer) executeTableMode(db *models.Database) error {
	for _, schema := range db.Schemas {
		for _, table := range schema.Tables {
			data := NewTableData(table, schema, db, w.options.Metadata)
			output, err := w.executeTemplate(data)
			if err != nil {
				return fmt.Errorf("failed to execute template for table %s.%s: %w", schema.Name, table.Name, err)
			}

			filename, err := w.generateFilename(data)
			if err != nil {
				return fmt.Errorf("failed to generate filename for table %s.%s: %w", schema.Name, table.Name, err)
			}

			if err := w.writeOutput(output, filename); err != nil {
				return fmt.Errorf("failed to write output for table %s.%s: %w", schema.Name, table.Name, err)
			}
		}
	}

	return nil
}

// loadTemplate loads and parses the template file
func (w *Writer) loadTemplate() error {
	// Read template file
	content, err := os.ReadFile(w.templatePath)
	if err != nil {
		return NewTemplateLoadError(fmt.Sprintf("failed to read template file: %s", w.templatePath), err)
	}

	// Parse template with function map
	tmpl, err := template.New(filepath.Base(w.templatePath)).Funcs(w.funcMap).Parse(string(content))
	if err != nil {
		return NewTemplateParseError(fmt.Sprintf("failed to parse template: %s", w.templatePath), err)
	}

	w.tmpl = tmpl
	return nil
}

// executeTemplate executes the template with the given data
func (w *Writer) executeTemplate(data *TemplateData) (string, error) {
	var buf bytes.Buffer
	if err := w.tmpl.Execute(&buf, data); err != nil {
		return "", NewTemplateExecuteError("failed to execute template", err)
	}

	return buf.String(), nil
}

// generateFilename generates a filename from the filename pattern
func (w *Writer) generateFilename(data *TemplateData) (string, error) {
	// Parse filename pattern as a template
	tmpl, err := template.New("filename").Funcs(w.funcMap).Parse(w.filenamePattern)
	if err != nil {
		return "", fmt.Errorf("invalid filename pattern: %w", err)
	}

	// Execute filename template
	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", fmt.Errorf("failed to generate filename: %w", err)
	}

	filename := buf.String()

	// If output path is a directory, join with generated filename
	if w.options.OutputPath != "" {
		// Check if output path is a directory
		info, err := os.Stat(w.options.OutputPath)
		if err == nil && info.IsDir() {
			filename = filepath.Join(w.options.OutputPath, filename)
		} else {
			// If it doesn't exist, check if it looks like a directory (ends with /)
			if strings.HasSuffix(w.options.OutputPath, string(filepath.Separator)) {
				filename = filepath.Join(w.options.OutputPath, filename)
			} else {
				// Use output path as base directory
				dir := filepath.Dir(w.options.OutputPath)
				if dir != "." {
					filename = filepath.Join(dir, filename)
				}
			}
		}
	}

	return filename, nil
}

// writeOutput writes the output to a file or stdout
func (w *Writer) writeOutput(content string, outputPath string) error {
	// If output path is empty, write to stdout
	if outputPath == "" {
		fmt.Print(content)
		return nil
	}

	// Ensure directory exists
	dir := filepath.Dir(outputPath)
	if dir != "." && dir != "" {
		if err := os.MkdirAll(dir, 0755); err != nil {
			return fmt.Errorf("failed to create directory %s: %w", dir, err)
		}
	}

	// Write to file
	if err := os.WriteFile(outputPath, []byte(content), 0644); err != nil {
		return fmt.Errorf("failed to write file %s: %w", outputPath, err)
	}

	return nil
}