import path from "node:path";

import { getUnixTime, parse, isMatch, format as formatDate } from "date-fns";
import { z } from "zod";

export const UpdateDirectionSchema = z.enum(["forward", "backward"]);
export type UpdateDirection = z.infer<typeof UpdateDirectionSchema>;

export const SourceKindSchema = z.enum(["wordpress", "html"]);
export type SourceKind = z.infer<typeof SourceKindSchema>;

export const SourceDateSchema = z.object({
  format: z.string().default("yyyy-LL-dd HH:mm"),
  pattern: z.string().nullable().optional(),
  replacement: z.string().nullable().optional(),
});
export type SourceDate = z.infer<typeof SourceDateSchema>;

export const SourceSelectorsSchema = z.object({
  articles: z.string().optional().nullable(),
  article_title: z.string().optional().nullable(),
  article_link: z.string().optional().nullable(),
  article_body: z.string().optional().nullable(),
  article_date: z.string().optional().nullable(),
  article_categories: z.string().optional().nullable(),
  pagination: z.string().default("ul.pagination > li a"),
});
export type SourceSelectors = z.infer<typeof SourceSelectorsSchema>;

const BaseSourceSchema = z.object({
  source_id: z.string(),
  source_url: z.string().url(),
  source_date: SourceDateSchema.default(SourceDateSchema.parse({})),
  source_kind: SourceKindSchema,
  categories: z.array(z.string()).default([]),
  supports_categories: z.boolean().default(false),
  requires_details: z.boolean().default(false),
  requires_rate_limit: z.boolean().default(false),
});

export const HtmlSourceConfigSchema = BaseSourceSchema.extend({
  source_kind: z.literal("html"),
  source_selectors: SourceSelectorsSchema.default(SourceSelectorsSchema.parse({})),
  pagination_template: z.string(),
});

export const WordPressSourceConfigSchema = BaseSourceSchema.extend({
  source_kind: z.literal("wordpress"),
  source_date: SourceDateSchema.default(
    SourceDateSchema.parse({ format: "yyyy-LL-dd'T'HH:mm:ss" }),
  ),
});

export type HtmlSourceConfig = z.infer<typeof HtmlSourceConfigSchema>;
export type WordPressSourceConfig = z.infer<typeof WordPressSourceConfigSchema>;
export type AnySourceConfig = HtmlSourceConfig | WordPressSourceConfig;

export const DateRangeSchema = z
  .object({
    start: z.number().int(),
    end: z.number().int(),
  })
  .superRefine((value, ctx) => {
    if (value.start === 0 || value.end === 0) {
      ctx.addIssue({
        code: z.ZodIssueCode.custom,
        message: "Timestamp cannot be zero",
      });
    }
    if (value.end < value.start) {
      ctx.addIssue({
        code: z.ZodIssueCode.custom,
        message: "End timestamp must be greater than or equal to start",
      });
    }
  });

export type DateRange = z.infer<typeof DateRangeSchema>;

export const PageRangeSchema = z
  .object({
    start: z.number().int().min(0),
    end: z.number().int().min(0),
  })
  .superRefine((value, ctx) => {
    if (value.end < value.start) {
      ctx.addIssue({
        code: z.ZodIssueCode.custom,
        message: "End page must be greater than or equal to start page",
      });
    }
  });

export type PageRange = z.infer<typeof PageRangeSchema>;

export const PageRangeSpecSchema = z
  .string()
  .regex(/^[0-9]+:[0-9]+$/, "Invalid page range format. Use start:end")
  .transform((spec) => {
    const [startText, endText] = spec.split(":");
    return {
      start: Number.parseInt(startText, 10),
      end: Number.parseInt(endText, 10),
    };
  });

const defaultDateFormat = "yyyy-LL-dd";

export const DateRangeSpecSchema = z
  .string()
  .regex(/.+:.+/, "Expected start:end format")
  .transform((spec) => {
    const [startRaw, endRaw] = spec.split(":");
    return { startRaw, endRaw };
  });

const parseDate = (value: string, format: string): Date => {
  if (!isMatch(value, format)) {
    throw new Error(`Invalid date '${value}' for format '${format}'`);
  }
  const parsed = parse(value, format, new Date());
  if (Number.isNaN(parsed.getTime())) {
    throw new Error(`Invalid date '${value}' for format '${format}'`);
  }
  return parsed;
};

export interface CreateDateRangeOptions {
  format?: string;
  separator?: string;
}

export const createDateRange = (
  spec: string,
  options: CreateDateRangeOptions = {},
): DateRange => {
  const { format = defaultDateFormat, separator = ":" } = options;
  if (!separator) {
    throw new Error("Separator cannot be empty");
  }

  const normalized = spec.replace(separator, ":");
  const parsedSpec = DateRangeSpecSchema.parse(normalized);

  const startDate = parseDate(parsedSpec.startRaw, format);
  const endDate = parseDate(parsedSpec.endRaw, format);

  const range = {
    start: getUnixTime(startDate),
    end: getUnixTime(endDate),
  };

  return DateRangeSchema.parse(range);
};

export const formatDateRange = (range: DateRange, fmt = defaultDateFormat): string => {
  const start = formatDate(new Date(range.start * 1000), fmt);
  const end = formatDate(new Date(range.end * 1000), fmt);
  return `${start}:${end}`;
};

export const isTimestampInRange = (range: DateRange, timestamp: number): boolean => {
  return range.start <= timestamp && timestamp <= range.end;
};

export const ProjectPathsSchema = z.object({
  root: z.string(),
  data: z.string(),
  logs: z.string(),
  configs: z.string(),
});
export type ProjectPaths = z.infer<typeof ProjectPathsSchema>;

export const resolveProjectPaths = (rootDir: string): ProjectPaths => {
  return ProjectPathsSchema.parse({
    root: rootDir,
    data: path.join(rootDir, "data", "dataset"),
    logs: path.join(rootDir, "data", "logs"),
    configs: path.join(rootDir, "config"),
  });
};

export const LoggingConfigSchema = z.object({
  level: z.string().default("INFO"),
  format: z
    .string()
    .default("%(asctime)s - %(name)s - %(levelname)s - %(message)s"),
  console_logging: z.boolean().default(true),
  file_logging: z.boolean().default(false),
  log_file: z.string().default("crawler.log"),
  max_log_size: z.number().int().positive().default(10 * 1024 * 1024),
  backup_count: z.number().int().nonnegative().default(5),
});
export type LoggingConfig = z.infer<typeof LoggingConfigSchema>;

export const ClientConfigSchema = z.object({
  timeout: z.number().positive().default(20),
  user_agent: z
    .string()
    .default("Basango/0.1 (+https://github.com/bernard-ng/basango)"),
  follow_redirects: z.boolean().default(true),
  verify_ssl: z.boolean().default(true),
  rotate: z.boolean().default(true),
  max_retries: z.number().int().nonnegative().default(3),
  backoff_initial: z.number().nonnegative().default(1),
  backoff_multiplier: z.number().positive().default(2),
  backoff_max: z.number().nonnegative().default(30),
  respect_retry_after: z.boolean().default(true),
});

export const CrawlerConfigSchema = z.object({
  source: z.union([HtmlSourceConfigSchema, WordPressSourceConfigSchema]).optional(),
  page_range: PageRangeSchema.optional(),
  date_range: DateRangeSchema.optional(),
  category: z.string().optional(),
  notify: z.boolean().default(false),
  is_update: z.boolean().default(false),
  use_multi_threading: z.boolean().default(false),
  max_workers: z.number().int().positive().default(5),
  direction: UpdateDirectionSchema.default("forward"),
});

export type ClientConfig = z.infer<typeof ClientConfigSchema>;
export type CrawlerConfig = z.infer<typeof CrawlerConfigSchema> & {
  source?: AnySourceConfig;
};

export const FetchConfigSchema = z.object({
  client: ClientConfigSchema.default(ClientConfigSchema.parse({})),
  crawler: CrawlerConfigSchema.default(CrawlerConfigSchema.parse({})),
});
export type FetchConfig = z.infer<typeof FetchConfigSchema>;

const SourcesConfigSchema = z.object({
  html: z.array(HtmlSourceConfigSchema).default([]),
  wordpress: z.array(WordPressSourceConfigSchema).default([]),
});

export type SourcesConfig = z.infer<typeof SourcesConfigSchema> & {
  find: (sourceId: string) => AnySourceConfig | undefined;
};

export const createSourcesConfig = (input: unknown): SourcesConfig => {
  const parsed = SourcesConfigSchema.parse(input);
  const resolver = (sourceId: string) =>
    [...parsed.html, ...parsed.wordpress].find((source) => source.source_id === sourceId);
  return Object.assign({ find: resolver }, parsed);
};

export const PipelineConfigSchema = z.object({
  paths: ProjectPathsSchema.default(resolveProjectPaths(process.cwd())),
  logging: LoggingConfigSchema.default(LoggingConfigSchema.parse({})),
  fetch: FetchConfigSchema.default(FetchConfigSchema.parse({})),
  sources: z
    .union([SourcesConfigSchema, z.undefined()])
    .transform((value) => createSourcesConfig(value ?? {})),
});

export type PipelineConfig = z.infer<typeof PipelineConfigSchema> & {
  sources: SourcesConfig;
};

export const mergePipelineConfig = (
  base: PipelineConfig,
  overrides: Partial<PipelineConfig>,
): PipelineConfig => {
  const paths = overrides.paths ?? base.paths;
  const logging = { ...base.logging, ...(overrides.logging ?? {}) };
  const fetch = {
    client: { ...base.fetch.client, ...(overrides.fetch?.client ?? {}) },
    crawler: { ...base.fetch.crawler, ...(overrides.fetch?.crawler ?? {}) },
  };

  const sources = createSourcesConfig({
    html: overrides.sources?.html ?? base.sources.html,
    wordpress: overrides.sources?.wordpress ?? base.sources.wordpress,
  });

  return {
    paths,
    logging,
    fetch,
    sources,
  };
};

export const resolveConfigPath = (basePath: string, env?: string): string => {
  if (!env || env === "development") {
    return basePath;
  }

  const ext = path.extname(basePath);
  const withoutExt = basePath.slice(0, basePath.length - ext.length);
  return `${withoutExt}.${env}${ext}`;
};

export const schemaToJSON = <T extends z.ZodTypeAny>(schema: T) => schema.toJSON();