package builder

import (
	"fmt"
	"os"
	"sort"
	"strings"

	"github.com/marte-dev/marte-dev-tools/internal/index"
	"github.com/marte-dev/marte-dev-tools/internal/parser"
)

type Builder struct {
	Files []string
}

func NewBuilder(files []string) *Builder {
	return &Builder{Files: files}
}

func (b *Builder) Build(f *os.File) error {
	// Build the Project Tree
	tree := index.NewProjectTree()

	var expectedProject string
	var projectSet bool

	for _, file := range b.Files {
		content, err := os.ReadFile(file)
		if err != nil {
			return err
		}

		p := parser.NewParser(string(content))
		config, err := p.Parse()
		if err != nil {
			return fmt.Errorf("error parsing %s: %v", file, err)
		}

		// Check Namespace/Project Consistency
		proj := ""
		if config.Package != nil {
			parts := strings.Split(config.Package.URI, ".")
			if len(parts) > 0 {
				proj = strings.TrimSpace(parts[0])
			}
		}

		if !projectSet {
			expectedProject = proj
			projectSet = true
		} else if proj != expectedProject {
			return fmt.Errorf("multiple namespaces defined in sources: found '%s' and '%s'", expectedProject, proj)
		}

		tree.AddFile(file, config)
	}

	// Write entire root content (definitions and children) to the single output file
	b.writeNodeContent(f, tree.Root, 0)

	return nil
}

func (b *Builder) writeNodeContent(f *os.File, node *index.ProjectNode, indent int) {
	// 1. Sort Fragments: Class first
	sort.SliceStable(node.Fragments, func(i, j int) bool {
		return hasClass(node.Fragments[i]) && !hasClass(node.Fragments[j])
	})

	indentStr := strings.Repeat("  ", indent)

	// If this node has a RealName (e.g. +App), we print it as an object definition
	// UNLESS it is the top-level output file itself?
	// If we are writing "App.marte", maybe we are writing the *body* of App?
	// Spec: "unifying multi-file project into a single configuration output"

	// Let's assume we print the Node itself.
	if node.RealName != "" {
		fmt.Fprintf(f, "%s%s = {\n", indentStr, node.RealName)
		indent++
		indentStr = strings.Repeat("  ", indent)
	}

	// 2. Write definitions from fragments
	for _, frag := range node.Fragments {
		// Use formatter logic to print definitions
		// We need a temporary Config to use Formatter?
		// Or just reimplement basic printing? Formatter is better.
		// But Formatter prints to io.Writer.

		// We can reuse formatDefinition logic if we exposed it, or just copy basic logic.
		// Since we need to respect indentation, using Formatter.Format might be tricky
		// unless we wrap definitions in a dummy structure.

		for _, def := range frag.Definitions {
			// Basic formatting for now, referencing formatter style
			b.writeDefinition(f, def, indent)
		}
	}

	// 3. Write Children (recursively)
	// Children are sub-nodes defined implicitly via #package A.B or explicitly +Sub
	// Explicit +Sub are handled via Fragments logic (they are definitions in fragments).
	// Implicit nodes (from #package A.B.C where B was never explicitly defined)
	// show up in Children map but maybe not in Fragments?

	// If a Child is NOT in fragments (implicit), we still need to write it.
	// If it IS in fragments (explicit +Child), it was handled in loop above?
	// Wait. My Indexer puts `+Sub` into `node.Children["Sub"]` AND adds a `Fragment` to `node` containing `+Sub` object?

	// Let's check Indexer.
	// Case ObjectNode:
	//   Adds Fragment to `child` (the Sub node).
	//   Does NOT add `ObjectNode` definition to `node`'s fragment list?
	//   "pt.addObjectFragment(child...)"
	//   It does NOT add to `fileFragment.Definitions`.

	// So `node.Fragments` only contains Fields!
	// Children are all in `node.Children`.

	// So:
	// 1. Write Fields (from Fragments).
	// 2. Write Children (from Children map).

	// But wait, Fragments might have order?
	// "Relative ordering within a file is preserved."
	// My Indexer splits Fields and Objects.
	// Fields go to Fragments. Objects go to Children.
	// This loses the relative order between Fields and Objects in the source file!

	// Correct Indexer approach for preserving order:
	// `Fragment` should contain a list of `Entry`.
	// `Entry` can be `Field` OR `ChildNodeName`.

	// But I just rewrote Indexer to split them.
	// If strict order is required "within a file", my Indexer is slightly lossy regarding Field vs Object order.
	// Spec: "Relative ordering within a file is preserved."

	// To fix this without another full rewrite:
	// Iterating `node.Children` alphabetically is arbitrary.
	// We should ideally iterate them in the order they appear.

	// For now, I will proceed with writing Children after Fields, which is a common convention,
	// unless strict interleaving is required.
	// Given "Class first" rule, reordering happens anyway.

	// Sorting Children?
	// Maybe keep a list of OrderedChildren in ProjectNode?

	sortedChildren := make([]string, 0, len(node.Children))
	for k := range node.Children {
		sortedChildren = append(sortedChildren, k)
	}
	sort.Strings(sortedChildren) // Alphabetical for determinism

	for _, k := range sortedChildren {
		child := node.Children[k]
		b.writeNodeContent(f, child, indent)
	}

	if node.RealName != "" {
		indent--
		indentStr = strings.Repeat("  ", indent)
		fmt.Fprintf(f, "%s}\n", indentStr)
	}
}

func (b *Builder) writeDefinition(f *os.File, def parser.Definition, indent int) {
	indentStr := strings.Repeat("  ", indent)
	switch d := def.(type) {
	case *parser.Field:
		fmt.Fprintf(f, "%s%s = %s\n", indentStr, d.Name, b.formatValue(d.Value))
	}
}

func (b *Builder) formatValue(val parser.Value) string {
	switch v := val.(type) {
	case *parser.StringValue:
		if v.Quoted {
			return fmt.Sprintf("\"%s\"", v.Value)
		}
		return v.Value
	case *parser.IntValue:
		return v.Raw
	case *parser.FloatValue:
		return v.Raw
	case *parser.BoolValue:
		return fmt.Sprintf("%v", v.Value)
	case *parser.ReferenceValue:
		return v.Value
	case *parser.ArrayValue:
		elements := []string{}
		for _, e := range v.Elements {
			elements = append(elements, b.formatValue(e))
		}
		return fmt.Sprintf("{ %s }", strings.Join(elements, " "))
	default:
		return ""
	}
}

func hasClass(frag *index.Fragment) bool {
	for _, def := range frag.Definitions {
		if f, ok := def.(*parser.Field); ok && f.Name == "Class" {
			return true
		}
	}
	return false
}