package swagger

import (
	"net/http"
	"sort"
	"strconv"
	"strings"
	"unicode"

	"github.com/gin-gonic/gin"
)

type Config struct {
	Title       string
	Version     string
	Description string
}

func EnabledForMode(mode string) bool {
	return !strings.EqualFold(strings.TrimSpace(mode), gin.ReleaseMode)
}

func Register(engine *gin.Engine, cfg Config) {
	cfg = withDefaults(cfg)

	engine.GET("/swagger", func(c *gin.Context) {
		c.Redirect(http.StatusMovedPermanently, "/swagger/index.html")
	})
	engine.GET("/swagger/", func(c *gin.Context) {
		c.Redirect(http.StatusMovedPermanently, "/swagger/index.html")
	})
	engine.GET("/swagger/index.html", func(c *gin.Context) {
		c.Data(http.StatusOK, "text/html; charset=utf-8", []byte(swaggerIndexHTML))
	})
	engine.GET("/swagger/openapi.json", func(c *gin.Context) {
		c.JSON(http.StatusOK, BuildOpenAPI(engine.Routes(), cfg))
	})
}

func BuildOpenAPI(routes gin.RoutesInfo, cfg Config) map[string]any {
	cfg = withDefaults(cfg)

	sort.Slice(routes, func(i, j int) bool {
		if routes[i].Path == routes[j].Path {
			return routes[i].Method < routes[j].Method
		}
		return routes[i].Path < routes[j].Path
	})

	paths := map[string]any{}
	tagSet := map[string]struct{}{}
	operationIDs := map[string]int{}

	for _, route := range routes {
		if shouldSkipRoute(route.Path) {
			continue
		}

		path := toOpenAPIPath(route.Path)
		method := strings.ToLower(route.Method)
		if method == "" {
			continue
		}

		pathItem, ok := paths[path].(map[string]any)
		if !ok {
			pathItem = map[string]any{}
			paths[path] = pathItem
		}

		tag := tagForPath(route.Path)
		tagSet[tag] = struct{}{}

		operationID := uniqueOperationID(method+"_"+sanitizeIdentifier(path), operationIDs)
		doc := docFor(route.Method, route.Path)
		operation := map[string]any{
			"tags":        []string{tag},
			"summary":     doc.Summary,
			"operationId": operationID,
			"responses":   responsesForRoute(route),
		}
		if doc.Description != "" {
			operation["description"] = doc.Description
		}

		if params := parametersForRoute(route); len(params) > 0 {
			operation["parameters"] = params
		}

		if body := requestBodyForRoute(route); body != nil {
			operation["requestBody"] = body
		}

		if security := securityForPath(route.Path); len(security) > 0 {
			operation["security"] = security
		}

		pathItem[method] = operation
	}

	tags := make([]map[string]string, 0, len(tagSet))
	for tag := range tagSet {
		tags = append(tags, map[string]string{"name": tag})
	}
	sort.Slice(tags, func(i, j int) bool {
		return tags[i]["name"] < tags[j]["name"]
	})

	return map[string]any{
		"openapi": "3.0.3",
		"info": map[string]any{
			"title":       cfg.Title,
			"version":     cfg.Version,
			"description": cfg.Description,
		},
		"servers": []map[string]string{
			{
				"url":         "/",
				"description": "Current host. When opened from admin-web, /api is proxied to tenant-api.",
			},
		},
		"tags":       tags,
		"paths":      paths,
		"components": components(),
	}
}

func withDefaults(cfg Config) Config {
	if strings.TrimSpace(cfg.Title) == "" {
		cfg.Title = "省心推 客户 API"
	}
	if strings.TrimSpace(cfg.Version) == "" {
		cfg.Version = "dev"
	}
	if strings.TrimSpace(cfg.Description) == "" {
		cfg.Description = "Auto-generated from registered Gin routes for admin-web testing. Request and response bodies are intentionally generic where handlers do not expose typed OpenAPI metadata."
	}
	return cfg
}

func shouldSkipRoute(path string) bool {
	return strings.HasPrefix(path, "/swagger") || strings.HasPrefix(path, "/api/internal/")
}

func toOpenAPIPath(path string) string {
	segments := strings.Split(path, "/")
	for i, segment := range segments {
		if strings.HasPrefix(segment, ":") && len(segment) > 1 {
			segments[i] = "{" + segment[1:] + "}"
			continue
		}
		if strings.HasPrefix(segment, "*") && len(segment) > 1 {
			segments[i] = "{" + segment[1:] + "}"
		}
	}
	return strings.Join(segments, "/")
}

func tagForPath(path string) string {
	segments := pathSegments(path)
	if len(segments) < 2 || segments[0] != "api" {
		return "General"
	}

	switch segments[1] {
	case "health":
		return "Health"
	case "auth":
		return "Auth"
	case "public":
		return "Public"
	case "desktop":
		if len(segments) >= 3 {
			return "Desktop " + titleSegment(segments[2])
		}
		return "Desktop"
	case "tenant":
		if len(segments) >= 4 && segments[2] == "kol" {
			return "Tenant KOL " + titleSegment(segments[3])
		}
		if len(segments) >= 3 {
			return "Tenant " + titleSegment(segments[2])
		}
		return "Tenant"
	default:
		return titleSegment(segments[1])
	}
}

func pathSegments(path string) []string {
	trimmed := strings.Trim(path, "/")
	if trimmed == "" {
		return nil
	}
	return strings.Split(trimmed, "/")
}

func titleSegment(segment string) string {
	parts := strings.FieldsFunc(segment, func(r rune) bool {
		return r == '-' || r == '_' || r == ':'
	})
	for i, part := range parts {
		switch strings.ToLower(part) {
		case "ai":
			parts[i] = "AI"
		case "kol":
			parts[i] = "KOL"
		default:
			parts[i] = strings.ToUpper(part[:1]) + strings.ToLower(part[1:])
		}
	}
	return strings.Join(parts, " ")
}

func uniqueOperationID(base string, seen map[string]int) string {
	if base == "" {
		base = "operation"
	}
	count := seen[base]
	seen[base] = count + 1
	if count == 0 {
		return base
	}
	return base + "_" + strconv.Itoa(count+1)
}

func sanitizeIdentifier(value string) string {
	var b strings.Builder
	lastUnderscore := false
	for _, r := range value {
		if unicode.IsLetter(r) || unicode.IsDigit(r) {
			b.WriteRune(unicode.ToLower(r))
			lastUnderscore = false
			continue
		}
		if !lastUnderscore {
			b.WriteByte('_')
			lastUnderscore = true
		}
	}
	return strings.Trim(b.String(), "_")
}

func parametersForRoute(route gin.RouteInfo) []map[string]any {
	params := make([]map[string]any, 0)
	params = append(params, pathParameters(route.Path)...)

	for _, name := range queryParameterNames(route) {
		params = append(params, queryParameter(name))
	}

	if requiresWorkspaceHeader(route.Path) {
		params = append(params, map[string]any{
			"name":        "X-Workspace-ID",
			"in":          "header",
			"required":    false,
			"description": "Optional workspace override. Defaults to the workspace in the access token.",
			"schema": map[string]any{
				"type":   "integer",
				"format": "int64",
			},
		})
	}

	return params
}

func pathParameters(path string) []map[string]any {
	segments := pathSegments(path)
	params := make([]map[string]any, 0)
	for _, segment := range segments {
		if len(segment) < 2 || (segment[0] != ':' && segment[0] != '*') {
			continue
		}
		name := segment[1:]
		params = append(params, map[string]any{
			"name":        name,
			"in":          "path",
			"required":    true,
			"description": "Route parameter `" + name + "`.",
			"schema": map[string]any{
				"type": "string",
			},
		})
	}
	return params
}

func queryParameterNames(route gin.RouteInfo) []string {
	if route.Method != http.MethodGet && route.Method != http.MethodDelete && route.Method != http.MethodPost {
		return nil
	}

	path := route.Path
	names := make([]string, 0)
	add := func(values ...string) {
		for _, value := range values {
			if value == "" || contains(names, value) {
				continue
			}
			names = append(names, value)
		}
	}

	switch {
	case strings.Contains(path, "/ops/site-domain-mappings"):
		add("page", "size", "keyword", "is_active")
	case strings.Contains(path, "/ops/object-storage/objects/detail") ||
		strings.Contains(path, "/ops/object-storage/objects/url") ||
		strings.Contains(path, "/ops/object-storage/objects/download-url") ||
		strings.Contains(path, "/ops/object-storage/objects/download"):
		add("key")
	case strings.Contains(path, "/ops/object-storage/objects"):
		add("prefix", "keyword", "continuation_token", "start_after", "recursive", "size", "key")
	case strings.Contains(path, "/ops/object-storage/folders"):
		add("prefix")
	case strings.Contains(path, "/workspace/ai-point-usage"):
		add("page", "page_size")
	case strings.Contains(path, "/tenant/articles"):
		add("page", "page_size", "generate_status", "publish_status", "source_type", "generation_mode", "template_id", "kol_prompt_id", "prompt_rule_id", "keyword", "created_from", "created_to")
	case strings.Contains(path, "/tenant/prompt-rules"):
		add("page", "page_size", "group_id", "ungrouped", "status", "keyword")
	case strings.Contains(path, "/tenant/schedules"):
		add("page", "page_size", "prompt_rule_id", "status", "keyword", "created_from", "created_to")
	case strings.Contains(path, "/tenant/instant-tasks"):
		add("page", "page_size", "prompt_rule_id", "status", "keyword", "created_from", "created_to")
	case strings.Contains(path, "/tenant/images"):
		add("page", "page_size", "folder_id", "q", "force")
	case strings.Contains(path, "/tenant/knowledge/items"):
		add("group_id")
	case strings.Contains(path, "/tenant/brands") && strings.Contains(path, "/questions"):
		add("keyword_id")
	case strings.Contains(path, "/tenant/monitoring/dashboard/composite"):
		add("brand_id", "keyword_id", "question_id", "days", "business_date", "ai_platform_id")
	case strings.Contains(path, "/tenant/monitoring/citation-summary"):
		add("days", "brand_id", "keyword_id", "question_id", "business_date", "ai_platform_id")
	case strings.Contains(path, "/tenant/monitoring/brands/"):
		add("ai_platform_id", "date_from", "date_to", "question_hash")
	case strings.Contains(path, "/tenant/kol/marketplace/packages"):
		add("industry", "keyword", "offset", "limit")
	case strings.Contains(path, "/tenant/kol/dashboard/trend"):
		add("period_days")
	case strings.Contains(path, "/tenant/accounts/"):
		add("undo")
	case strings.Contains(path, "/tenant/publish-tasks"):
		add("page", "page_size", "limit", "title")
	case strings.Contains(path, "/desktop/accounts"):
		add("client", "if_sync_version")
	case strings.Contains(path, "/desktop/publish-tasks"):
		add("page", "page_size", "limit", "title")
	case strings.Contains(path, "/templates/") && strings.Contains(path, "_task_result"):
		add("task_id")
	case strings.Contains(path, "/public/assets/"):
		add("format")
	}

	return names
}

func queryParameter(name string) map[string]any {
	return map[string]any{
		"name":     name,
		"in":       "query",
		"required": false,
		"schema":   schemaForQueryParameter(name),
	}
}

func schemaForQueryParameter(name string) map[string]any {
	switch name {
	case "page", "page_size", "limit", "offset", "days", "period_days", "size":
		return map[string]any{"type": "integer"}
	case "brand_id", "keyword_id", "question_id", "template_id", "kol_prompt_id", "prompt_rule_id", "group_id", "folder_id", "if_sync_version":
		return map[string]any{"type": "integer", "format": "int64"}
	case "force":
		return map[string]any{"type": "string", "enum": []string{"1"}}
	case "ungrouped", "undo", "recursive", "is_active":
		return map[string]any{"type": "string", "enum": []string{"true", "false"}}
	case "created_from", "created_to", "date_from", "date_to", "business_date":
		return map[string]any{"type": "string", "format": "date"}
	default:
		return map[string]any{"type": "string"}
	}
}

func requestBodyForRoute(route gin.RouteInfo) map[string]any {
	switch route.Method {
	case http.MethodPost, http.MethodPut, http.MethodPatch:
	default:
		return nil
	}

	if isMultipartRoute(route) {
		return multipartRequestBody(route.Path)
	}

	return map[string]any{
		"required": false,
		"content": map[string]any{
			"application/json": map[string]any{
				"schema": map[string]any{
					"type":                 "object",
					"additionalProperties": true,
				},
				"example": map[string]any{},
			},
		},
	}
}

func isMultipartRoute(route gin.RouteInfo) bool {
	if route.Method != http.MethodPost {
		return false
	}
	path := route.Path
	return path == "/api/tenant/images" ||
		path == "/api/desktop/bug-reports" ||
		path == "/api/desktop/clients/bug-reports" ||
		path == "/api/ops/site-domain-mappings/import" ||
		path == "/api/ops/object-storage/objects/upload" ||
		path == "/api/ops/desktop-client/releases/upload" ||
		path == "/api/tenant/knowledge/items/file" ||
		path == "/api/tenant/kol/manage/profile/avatar" ||
		path == "/api/tenant/articles/:id/images"
}

func multipartRequestBody(path string) map[string]any {
	properties := map[string]any{
		"file": map[string]any{
			"type":   "string",
			"format": "binary",
		},
	}
	required := []string{"file"}

	if path == "/api/desktop/bug-reports" || path == "/api/desktop/clients/bug-reports" {
		properties = map[string]any{
			"upload_file_minidump": map[string]any{
				"type":        "string",
				"format":      "binary",
				"description": "Electron crashReporter 默认上传的 minidump 字段；手动反馈也可用 dump 或 file 字段。",
			},
			"report_type":      map[string]any{"type": "string", "enum": []string{"crash", "bug"}},
			"severity":         map[string]any{"type": "string", "enum": []string{"low", "medium", "high", "critical"}},
			"title":            map[string]any{"type": "string"},
			"description":      map[string]any{"type": "string"},
			"runtime_snapshot": map[string]any{"type": "string"},
			"app_log_tail":     map[string]any{"type": "string"},
		}
		required = nil
	}

	if path == "/api/tenant/images" {
		properties["folder_id"] = map[string]any{"type": "string"}
	}
	if path == "/api/tenant/knowledge/items/file" {
		properties["group_id"] = map[string]any{"type": "string"}
		properties["name"] = map[string]any{"type": "string"}
		required = append(required, "group_id")
	}

	return map[string]any{
		"required": true,
		"content": map[string]any{
			"multipart/form-data": map[string]any{
				"schema": map[string]any{
					"type":       "object",
					"properties": properties,
					"required":   required,
				},
			},
		},
	}
}

func responsesForRoute(route gin.RouteInfo) map[string]any {
	successContent := map[string]any{
		"application/json": map[string]any{
			"schema": map[string]any{
				"$ref": "#/components/schemas/ApiEnvelope",
			},
		},
	}
	if strings.HasSuffix(route.Path, "/stream") {
		successContent = map[string]any{
			"text/event-stream": map[string]any{
				"schema": map[string]any{"type": "string"},
			},
		}
	}

	responses := map[string]any{
		"200": map[string]any{
			"description": "OK",
			"content":     successContent,
		},
		"400": errorResponse("Bad Request"),
		"401": errorResponse("Unauthorized"),
		"403": errorResponse("Forbidden"),
		"404": errorResponse("Not Found"),
		"500": errorResponse("Internal Server Error"),
	}

	if route.Method == http.MethodPost {
		responses["201"] = map[string]any{
			"description": "Created",
			"content": map[string]any{
				"application/json": map[string]any{
					"schema": map[string]any{
						"$ref": "#/components/schemas/ApiEnvelope",
					},
				},
			},
		}
	}

	return responses
}

func errorResponse(description string) map[string]any {
	return map[string]any{
		"description": description,
		"content": map[string]any{
			"application/json": map[string]any{
				"schema": map[string]any{
					"$ref": "#/components/schemas/ApiError",
				},
			},
		},
	}
}

func securityForPath(path string) []map[string][]string {
	if path == "/api/auth/password-key" ||
		path == "/api/auth/login" || path == "/api/auth/refresh" ||
		path == "/api/desktop/releases/latest" ||
		path == "/api/desktop/releases/download-url" ||
		path == "/api/desktop/releases/updater/:platform/:arch/:channel/:version" ||
		path == "/api/desktop/releases/updater/:platform/:arch/:channel/:version/:feed" ||
		strings.HasPrefix(path, "/api/health/") ||
		strings.HasPrefix(path, "/api/public/") {
		return nil
	}
	if strings.HasPrefix(path, "/api/") {
		return []map[string][]string{{"bearerAuth": []string{}}}
	}
	return nil
}

func requiresWorkspaceHeader(path string) bool {
	return path == "/api/auth/me" ||
		path == "/api/auth/logout" ||
		path == "/api/desktop/clients/register" ||
		strings.HasPrefix(path, "/api/tenant/")
}

func components() map[string]any {
	return map[string]any{
		"securitySchemes": map[string]any{
			"bearerAuth": map[string]any{
				"type":         "http",
				"scheme":       "bearer",
				"bearerFormat": "JWT",
				"description":  "Admin-web endpoints use the tenant access token. Desktop client endpoints also use Bearer, with the desktop client token.",
			},
		},
		"schemas": map[string]any{
			"ApiEnvelope": map[string]any{
				"type": "object",
				"properties": map[string]any{
					"code":       map[string]any{"type": "integer", "example": 0},
					"message":    map[string]any{"type": "string", "example": "ok"},
					"data":       map[string]any{"description": "Response payload."},
					"request_id": map[string]any{"type": "string"},
				},
			},
			"ApiError": map[string]any{
				"type": "object",
				"properties": map[string]any{
					"code":       map[string]any{"type": "integer"},
					"message":    map[string]any{"type": "string"},
					"detail":     map[string]any{"type": "string"},
					"request_id": map[string]any{"type": "string"},
				},
			},
		},
	}
}

func contains(values []string, expected string) bool {
	for _, value := range values {
		if value == expected {
			return true
		}
	}
	return false
}

const swaggerIndexHTML = `<!doctype html>
<html lang="zh-CN">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>省心推 API Swagger</title>
    <link rel="stylesheet" href="https://unpkg.com/swagger-ui-dist@5/swagger-ui.css" />
    <style>
      body {
        margin: 0;
        background: #f6f7f9;
      }
      .swagger-ui .topbar {
        display: none;
      }
      .swagger-ui .info {
        margin: 32px 0 24px;
      }
    </style>
  </head>
  <body>
    <div id="swagger-ui"></div>
    <script src="https://unpkg.com/swagger-ui-dist@5/swagger-ui-bundle.js"></script>
    <script>
      window.ui = SwaggerUIBundle({
        url: "/swagger/openapi.json",
        dom_id: "#swagger-ui",
        deepLinking: true,
        displayRequestDuration: true,
        docExpansion: "none",
        persistAuthorization: true,
        tryItOutEnabled: true
      });
    </script>
  </body>
</html>`