// Package parser provides Organization Chart parsing
package parser

import (
	"fmt"
	"strings"

	"mermaid-go/pkg/ast"
	"mermaid-go/pkg/lexer"
)

// OrganizationParser implements Organization Chart parsing
type OrganizationParser struct {
	tokens  []lexer.Token
	current int
	diagram *ast.OrganizationDiagram
}

// NewOrganizationParser creates a new Organization parser
func NewOrganizationParser() *OrganizationParser {
	return &OrganizationParser{
		diagram: ast.NewOrganizationDiagram(),
	}
}

// Parse parses Organization Chart syntax
func (p *OrganizationParser) Parse(input string) (*ast.OrganizationDiagram, error) {
	// Tokenize
	l := lexer.NewLexer(input)
	tokens, err := l.Tokenize()
	if err != nil {
		return nil, fmt.Errorf("lexical analysis failed: %w", err)
	}

	// Filter tokens
	p.tokens = lexer.FilterTokens(tokens)
	p.current = 0
	p.diagram = ast.NewOrganizationDiagram()

	// Parse document
	err = p.parseDocument()
	if err != nil {
		return nil, fmt.Errorf("syntax analysis failed: %w", err)
	}

	return p.diagram, nil
}

// parseDocument parses the Organization Chart document
func (p *OrganizationParser) parseDocument() error {
	// Expect organization or orgChart
	if !p.check(lexer.TokenID) ||
		(p.peek().Value != "organization" && p.peek().Value != "orgChart") {
		return p.error("expected 'organization' or 'orgChart'")
	}
	p.advance()

	// Parse statements
	for !p.isAtEnd() {
		if err := p.parseStatement(); err != nil {
			return err
		}
	}

	// Build hierarchy after parsing all nodes
	p.buildHierarchy()

	return nil
}

// parseStatement parses individual Organization Chart statements
func (p *OrganizationParser) parseStatement() error {
	if p.isAtEnd() {
		return nil
	}

	switch {
	case p.check(lexer.TokenNewline):
		p.advance() // Skip newlines
		return nil
	case p.checkKeyword("title"):
		return p.parseTitle()
	case p.check(lexer.TokenID):
		// Node definition
		return p.parseNode()
	default:
		token := p.peek()
		return p.error(fmt.Sprintf("unexpected token: %s", token.Value))
	}
}

// parseTitle parses title statements
func (p *OrganizationParser) parseTitle() error {
	p.advance() // consume 'title'

	var titleParts []string
	for !p.check(lexer.TokenNewline) && !p.isAtEnd() {
		titleParts = append(titleParts, p.advance().Value)
	}

	if len(titleParts) > 0 {
		title := strings.TrimSpace(strings.Join(titleParts, " "))
		p.diagram.Title = &title
	}

	return nil
}

// parseNode parses node definitions
func (p *OrganizationParser) parseNode() error {
	// Parse node ID
	nodeID := p.advance().Value

	node := &ast.OrganizationNode{
		ID:         nodeID,
		Name:       nodeID, // Default name is ID
		Level:      0,      // Will be calculated later
		Children:   make([]*ast.OrganizationNode, 0),
		CssClasses: make([]string, 0),
		Styles:     make([]string, 0),
	}

	// Parse node properties
	for !p.check(lexer.TokenNewline) && !p.isAtEnd() {
		if p.check(lexer.TokenOpenBracket) {
			p.advance() // consume '['

			// Parse node title/name
			var titleParts []string
			for !p.check(lexer.TokenCloseBracket) && !p.isAtEnd() {
				titleParts = append(titleParts, p.advance().Value)
			}

			if len(titleParts) > 0 {
				title := strings.TrimSpace(strings.Join(titleParts, " "))
				node.Name = title
			}

			if p.check(lexer.TokenCloseBracket) {
				p.advance() // consume ']'
			}
		} else if p.check(lexer.TokenArrowSolid) || p.check(lexer.TokenMinus) {
			// Parse relationship
			p.advance() // consume arrow or minus

			// Skip additional arrow characters
			for p.check(lexer.TokenMinus) || p.check(lexer.TokenArrowSolid) {
				p.advance()
			}

			// Parse child node
			if p.check(lexer.TokenID) {
				childID := p.advance().Value

				// Create or find child node
				childNode := p.diagram.FindNode(childID)
				if childNode == nil {
					childNode = &ast.OrganizationNode{
						ID:         childID,
						Name:       childID,
						Level:      node.Level + 1,
						Children:   make([]*ast.OrganizationNode, 0),
						CssClasses: make([]string, 0),
						Styles:     make([]string, 0),
					}
					p.diagram.AddNode(childNode)
				}

				// Establish parent-child relationship
				node.AddChild(childNode)
			}
		} else {
			p.advance() // consume unknown token
		}
	}

	p.diagram.AddNode(node)
	return nil
}

// buildHierarchy builds the hierarchical structure
func (p *OrganizationParser) buildHierarchy() {
	// Find root nodes (nodes without parents)
	for _, node := range p.diagram.Nodes {
		if node.Parent == nil && p.diagram.Root == nil {
			p.diagram.Root = node
			break
		}
	}

	// Calculate levels
	if p.diagram.Root != nil {
		p.calculateLevels(p.diagram.Root, 0)
	}
}

// calculateLevels recursively calculates node levels
func (p *OrganizationParser) calculateLevels(node *ast.OrganizationNode, level int) {
	node.Level = level
	for _, child := range node.Children {
		p.calculateLevels(child, level+1)
	}
}

// Helper methods
func (p *OrganizationParser) check(tokenType lexer.TokenType) bool {
	if p.isAtEnd() {
		return false
	}
	return p.peek().Type == tokenType
}

func (p *OrganizationParser) checkKeyword(keyword string) bool {
	if p.isAtEnd() {
		return false
	}
	token := p.peek()
	return token.Type == lexer.TokenID && strings.ToLower(token.Value) == strings.ToLower(keyword)
}

func (p *OrganizationParser) advance() lexer.Token {
	if !p.isAtEnd() {
		p.current++
	}
	return p.previous()
}

func (p *OrganizationParser) isAtEnd() bool {
	return p.current >= len(p.tokens) || p.peek().Type == lexer.TokenEOF
}

func (p *OrganizationParser) peek() lexer.Token {
	if p.current >= len(p.tokens) {
		return lexer.Token{Type: lexer.TokenEOF}
	}
	return p.tokens[p.current]
}

func (p *OrganizationParser) previous() lexer.Token {
	if p.current <= 0 {
		return lexer.Token{Type: lexer.TokenEOF}
	}
	return p.tokens[p.current-1]
}

func (p *OrganizationParser) error(message string) error {
	token := p.peek()
	return fmt.Errorf("parse error at line %d, column %d: %s (got %s)",
		token.Line, token.Column, message, token.Type.String())
}