package synthesizer

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/router-for-me/CLIProxyAPI/v6/internal/runtime/geminicli"
	coreauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
)

// FileSynthesizer generates Auth entries from OAuth JSON files.
// It handles file-based authentication and Gemini virtual auth generation.
type FileSynthesizer struct{}

// NewFileSynthesizer creates a new FileSynthesizer instance.
func NewFileSynthesizer() *FileSynthesizer {
	return &FileSynthesizer{}
}

// Synthesize generates Auth entries from auth files in the auth directory.
func (s *FileSynthesizer) Synthesize(ctx *SynthesisContext) ([]*coreauth.Auth, error) {
	out := make([]*coreauth.Auth, 0, 16)
	if ctx == nil || ctx.AuthDir == "" {
		return out, nil
	}

	entries, err := os.ReadDir(ctx.AuthDir)
	if err != nil {
		// Not an error if directory doesn't exist
		return out, nil
	}

	now := ctx.Now
	cfg := ctx.Config

	for _, e := range entries {
		if e.IsDir() {
			continue
		}
		name := e.Name()
		if !strings.HasSuffix(strings.ToLower(name), ".json") {
			continue
		}
		full := filepath.Join(ctx.AuthDir, name)
		data, errRead := os.ReadFile(full)
		if errRead != nil || len(data) == 0 {
			continue
		}
		var metadata map[string]any
		if errUnmarshal := json.Unmarshal(data, &metadata); errUnmarshal != nil {
			continue
		}
		t, _ := metadata["type"].(string)
		if t == "" {
			continue
		}
		provider := strings.ToLower(t)
		if provider == "gemini" {
			provider = "gemini-cli"
		}
		label := provider
		if email, _ := metadata["email"].(string); email != "" {
			label = email
		}
		// Use relative path under authDir as ID to stay consistent with the file-based token store
		id := full
		if rel, errRel := filepath.Rel(ctx.AuthDir, full); errRel == nil && rel != "" {
			id = rel
		}

		proxyURL := ""
		if p, ok := metadata["proxy_url"].(string); ok {
			proxyURL = p
		}

		prefix := ""
		if rawPrefix, ok := metadata["prefix"].(string); ok {
			trimmed := strings.TrimSpace(rawPrefix)
			trimmed = strings.Trim(trimmed, "/")
			if trimmed != "" && !strings.Contains(trimmed, "/") {
				prefix = trimmed
			}
		}

		a := &coreauth.Auth{
			ID:       id,
			Provider: provider,
			Label:    label,
			Prefix:   prefix,
			Status:   coreauth.StatusActive,
			Attributes: map[string]string{
				"source": full,
				"path":   full,
			},
			ProxyURL:  proxyURL,
			Metadata:  metadata,
			CreatedAt: now,
			UpdatedAt: now,
		}
		ApplyAuthExcludedModelsMeta(a, cfg, nil, "oauth")
		if provider == "gemini-cli" {
			if virtuals := SynthesizeGeminiVirtualAuths(a, metadata, now); len(virtuals) > 0 {
				for _, v := range virtuals {
					ApplyAuthExcludedModelsMeta(v, cfg, nil, "oauth")
				}
				out = append(out, a)
				out = append(out, virtuals...)
				continue
			}
		}
		out = append(out, a)
	}
	return out, nil
}

// SynthesizeGeminiVirtualAuths creates virtual Auth entries for multi-project Gemini credentials.
// It disables the primary auth and creates one virtual auth per project.
func SynthesizeGeminiVirtualAuths(primary *coreauth.Auth, metadata map[string]any, now time.Time) []*coreauth.Auth {
	if primary == nil || metadata == nil {
		return nil
	}
	projects := splitGeminiProjectIDs(metadata)
	if len(projects) <= 1 {
		return nil
	}
	email, _ := metadata["email"].(string)
	shared := geminicli.NewSharedCredential(primary.ID, email, metadata, projects)
	primary.Disabled = true
	primary.Status = coreauth.StatusDisabled
	primary.Runtime = shared
	if primary.Attributes == nil {
		primary.Attributes = make(map[string]string)
	}
	primary.Attributes["gemini_virtual_primary"] = "true"
	primary.Attributes["virtual_children"] = strings.Join(projects, ",")
	source := primary.Attributes["source"]
	authPath := primary.Attributes["path"]
	originalProvider := primary.Provider
	if originalProvider == "" {
		originalProvider = "gemini-cli"
	}
	label := primary.Label
	if label == "" {
		label = originalProvider
	}
	virtuals := make([]*coreauth.Auth, 0, len(projects))
	for _, projectID := range projects {
		attrs := map[string]string{
			"runtime_only":           "true",
			"gemini_virtual_parent":  primary.ID,
			"gemini_virtual_project": projectID,
		}
		if source != "" {
			attrs["source"] = source
		}
		if authPath != "" {
			attrs["path"] = authPath
		}
		metadataCopy := map[string]any{
			"email":             email,
			"project_id":        projectID,
			"virtual":           true,
			"virtual_parent_id": primary.ID,
			"type":              metadata["type"],
		}
		proxy := strings.TrimSpace(primary.ProxyURL)
		if proxy != "" {
			metadataCopy["proxy_url"] = proxy
		}
		virtual := &coreauth.Auth{
			ID:         buildGeminiVirtualID(primary.ID, projectID),
			Provider:   originalProvider,
			Label:      fmt.Sprintf("%s [%s]", label, projectID),
			Status:     coreauth.StatusActive,
			Attributes: attrs,
			Metadata:   metadataCopy,
			ProxyURL:   primary.ProxyURL,
			Prefix:     primary.Prefix,
			CreatedAt:  primary.CreatedAt,
			UpdatedAt:  primary.UpdatedAt,
			Runtime:    geminicli.NewVirtualCredential(projectID, shared),
		}
		virtuals = append(virtuals, virtual)
	}
	return virtuals
}

// splitGeminiProjectIDs extracts and deduplicates project IDs from metadata.
func splitGeminiProjectIDs(metadata map[string]any) []string {
	raw, _ := metadata["project_id"].(string)
	trimmed := strings.TrimSpace(raw)
	if trimmed == "" {
		return nil
	}
	parts := strings.Split(trimmed, ",")
	result := make([]string, 0, len(parts))
	seen := make(map[string]struct{}, len(parts))
	for _, part := range parts {
		id := strings.TrimSpace(part)
		if id == "" {
			continue
		}
		if _, ok := seen[id]; ok {
			continue
		}
		seen[id] = struct{}{}
		result = append(result, id)
	}
	return result
}

// buildGeminiVirtualID constructs a virtual auth ID from base ID and project ID.
func buildGeminiVirtualID(baseID, projectID string) string {
	project := strings.TrimSpace(projectID)
	if project == "" {
		project = "project"
	}
	replacer := strings.NewReplacer("/", "_", "\\", "_", " ", "_")
	return fmt.Sprintf("%s::%s", baseID, replacer.Replace(project))
}