import fs from "fs/promises"
import path from "path"
import { fileURLToPath } from "url"
import z from "zod"
import { Cause, Context, Effect, Layer, Queue, Stream } from "effect"
import { ripgrep } from "ripgrep"

import { Filesystem } from "@/util"
import { Log } from "@/util"

export namespace Ripgrep {
  const log = Log.create({ service: "ripgrep" })

  const Stats = z.object({
    elapsed: z.object({
      secs: z.number(),
      nanos: z.number(),
      human: z.string(),
    }),
    searches: z.number(),
    searches_with_match: z.number(),
    bytes_searched: z.number(),
    bytes_printed: z.number(),
    matched_lines: z.number(),
    matches: z.number(),
  })

  const Begin = z.object({
    type: z.literal("begin"),
    data: z.object({
      path: z.object({
        text: z.string(),
      }),
    }),
  })

  export const Match = z.object({
    type: z.literal("match"),
    data: z.object({
      path: z.object({
        text: z.string(),
      }),
      lines: z.object({
        text: z.string(),
      }),
      line_number: z.number(),
      absolute_offset: z.number(),
      submatches: z.array(
        z.object({
          match: z.object({
            text: z.string(),
          }),
          start: z.number(),
          end: z.number(),
        }),
      ),
    }),
  })

  const End = z.object({
    type: z.literal("end"),
    data: z.object({
      path: z.object({
        text: z.string(),
      }),
      binary_offset: z.number().nullable(),
      stats: Stats,
    }),
  })

  const Summary = z.object({
    type: z.literal("summary"),
    data: z.object({
      elapsed_total: z.object({
        human: z.string(),
        nanos: z.number(),
        secs: z.number(),
      }),
      stats: Stats,
    }),
  })

  const Result = z.union([Begin, Match, End, Summary])

  export type Result = z.infer<typeof Result>
  export type Match = z.infer<typeof Match>
  export type Item = Match["data"]
  export type Begin = z.infer<typeof Begin>
  export type End = z.infer<typeof End>
  export type Summary = z.infer<typeof Summary>
  export type Row = Match["data"]

  export interface SearchResult {
    items: Item[]
    partial: boolean
  }

  export interface FilesInput {
    cwd: string
    glob?: string[]
    hidden?: boolean
    follow?: boolean
    maxDepth?: number
    signal?: AbortSignal
  }

  export interface SearchInput {
    cwd: string
    pattern: string
    glob?: string[]
    limit?: number
    follow?: boolean
    file?: string[]
    signal?: AbortSignal
  }

  export interface TreeInput {
    cwd: string
    limit?: number
    signal?: AbortSignal
  }

  export interface Interface {
    readonly files: (input: FilesInput) => Stream.Stream<string, Error>
    readonly tree: (input: TreeInput) => Effect.Effect<string, Error>
    readonly search: (input: SearchInput) => Effect.Effect<SearchResult, Error>
  }

  export class Service extends Context.Service<Service, Interface>()("@opencode/Ripgrep") {}

  type Run = { kind: "files" | "search"; cwd: string; args: string[] }

  type WorkerResult = {
    type: "result"
    code: number
    stdout: string
    stderr: string
  }

  type WorkerLine = {
    type: "line"
    line: string
  }

  type WorkerDone = {
    type: "done"
    code: number
    stderr: string
  }

  type WorkerError = {
    type: "error"
    error: {
      message: string
      name?: string
      stack?: string
    }
  }

  function env() {
    const env = Object.fromEntries(
      Object.entries(process.env).filter((item): item is [string, string] => item[1] !== undefined),
    )
    delete env.RIPGREP_CONFIG_PATH
    return env
  }

  function text(input: unknown) {
    if (typeof input === "string") return input
    if (input instanceof ArrayBuffer) return Buffer.from(input).toString()
    if (ArrayBuffer.isView(input)) return Buffer.from(input.buffer, input.byteOffset, input.byteLength).toString()
    return String(input)
  }

  function toError(input: unknown) {
    if (input instanceof Error) return input
    if (typeof input === "string") return new Error(input)
    return new Error(String(input))
  }

  function abort(signal?: AbortSignal) {
    const err = signal?.reason
    if (err instanceof Error) return err
    const out = new Error("Aborted")
    out.name = "AbortError"
    return out
  }

  function error(stderr: string, code: number) {
    const err = new Error(stderr.trim() || `ripgrep failed with code ${code}`)
    err.name = "RipgrepError"
    return err
  }

  function clean(file: string) {
    return path.normalize(file.replace(/^\.[\\/]/, ""))
  }

  function row(data: Row): Row {
    return {
      ...data,
      path: {
        ...data.path,
        text: clean(data.path.text),
      },
    }
  }

  function opts(cwd: string) {
    return {
      env: env(),
      preopens: { ".": cwd },
    }
  }

  function check(cwd: string) {
    return Effect.tryPromise({
      try: () => fs.stat(cwd).catch(() => undefined),
      catch: toError,
    }).pipe(
      Effect.flatMap((stat) =>
        stat?.isDirectory()
          ? Effect.void
          : Effect.fail(
              Object.assign(new Error(`No such file or directory: '${cwd}'`), {
                code: "ENOENT",
                errno: -2,
                path: cwd,
              }),
            ),
      ),
    )
  }

  function filesArgs(input: FilesInput) {
    const args = ["--files", "--glob=!.git/*"]
    if (input.follow) args.push("--follow")
    if (input.hidden !== false) args.push("--hidden")
    if (input.maxDepth !== undefined) args.push(`--max-depth=${input.maxDepth}`)
    if (input.glob) {
      for (const glob of input.glob) {
        args.push(`--glob=${glob}`)
      }
    }
    args.push(".")
    return args
  }

  function searchArgs(input: SearchInput) {
    const args = ["--json", "--hidden", "--glob=!.git/*", "--no-messages"]
    if (input.follow) args.push("--follow")
    if (input.glob) {
      for (const glob of input.glob) {
        args.push(`--glob=${glob}`)
      }
    }
    if (input.limit) args.push(`--max-count=${input.limit}`)
    args.push("--", input.pattern, ...(input.file ?? ["."]))
    return args
  }

  function parse(stdout: string) {
    return stdout
      .trim()
      .split(/\r?\n/)
      .filter(Boolean)
      .map((line) => Result.parse(JSON.parse(line)))
      .flatMap((item) => (item.type === "match" ? [row(item.data)] : []))
  }

  declare const OPENCODE_RIPGREP_WORKER_PATH: string

  function target(): Effect.Effect<string | URL, Error> {
    if (typeof OPENCODE_RIPGREP_WORKER_PATH !== "undefined") {
      return Effect.succeed(OPENCODE_RIPGREP_WORKER_PATH)
    }
    const js = new URL("./ripgrep.worker.js", import.meta.url)
    return Effect.tryPromise({
      try: () => Filesystem.exists(fileURLToPath(js)),
      catch: toError,
    }).pipe(Effect.map((exists) => (exists ? js : new URL("./ripgrep.worker.ts", import.meta.url))))
  }

  function worker() {
    return target().pipe(Effect.flatMap((file) => Effect.sync(() => new Worker(file, { env: env() }))))
  }

  function drain(buf: string, chunk: unknown, push: (line: string) => void) {
    const lines = (buf + text(chunk)).split(/\r?\n/)
    buf = lines.pop() || ""
    for (const line of lines) {
      if (line) push(line)
    }
    return buf
  }

  function fail(queue: Queue.Queue<string, Error | Cause.Done>, err: Error) {
    Queue.failCauseUnsafe(queue, Cause.fail(err))
  }

  function searchDirect(input: SearchInput) {
    return Effect.tryPromise({
      try: () =>
        ripgrep(searchArgs(input), {
          buffer: true,
          ...opts(input.cwd),
        }),
      catch: toError,
    }).pipe(
      Effect.flatMap((ret) => {
        const out = ret.stdout ?? ""
        if (ret.code !== 0 && ret.code !== 1 && ret.code !== 2) {
          return Effect.fail(error(ret.stderr ?? "", ret.code ?? 1))
        }
        return Effect.sync(() => ({
          items: ret.code === 1 ? [] : parse(out),
          partial: ret.code === 2,
        }))
      }),
    )
  }

  function searchWorker(input: SearchInput) {
    if (input.signal?.aborted) return Effect.fail(abort(input.signal))

    return Effect.acquireUseRelease(
      worker(),
      (w) =>
        Effect.callback<SearchResult, Error>((resume, signal) => {
          let open = true
          const done = (effect: Effect.Effect<SearchResult, Error>) => {
            if (!open) return
            open = false
            resume(effect)
          }
          const onabort = () => done(Effect.fail(abort(input.signal)))

          w.onerror = (evt) => {
            done(Effect.fail(toError(evt.error ?? evt.message)))
          }
          w.onmessage = (evt: MessageEvent<WorkerResult | WorkerError>) => {
            const msg = evt.data
            if (msg.type === "error") {
              done(Effect.fail(Object.assign(new Error(msg.error.message), msg.error)))
              return
            }
            if (msg.code === 1) {
              done(Effect.succeed({ items: [], partial: false }))
              return
            }
            if (msg.code !== 0 && msg.code !== 1 && msg.code !== 2) {
              done(Effect.fail(error(msg.stderr, msg.code)))
              return
            }
            done(
              Effect.sync(() => ({
                items: parse(msg.stdout),
                partial: msg.code === 2,
              })),
            )
          }

          input.signal?.addEventListener("abort", onabort, { once: true })
          signal.addEventListener("abort", onabort, { once: true })
          w.postMessage({
            kind: "search",
            cwd: input.cwd,
            args: searchArgs(input),
          } satisfies Run)

          return Effect.sync(() => {
            input.signal?.removeEventListener("abort", onabort)
            signal.removeEventListener("abort", onabort)
            w.onerror = null
            w.onmessage = null
          })
        }),
      (w) => Effect.sync(() => w.terminate()),
    )
  }

  function filesDirect(input: FilesInput) {
    return Stream.callback<string, Error>(
      Effect.fnUntraced(function* (queue: Queue.Queue<string, Error | Cause.Done>) {
        let buf = ""
        let err = ""

        const out = {
          write(chunk: unknown) {
            buf = drain(buf, chunk, (line) => {
              Queue.offerUnsafe(queue, clean(line))
            })
          },
        }

        const stderr = {
          write(chunk: unknown) {
            err += text(chunk)
          },
        }

        yield* Effect.forkScoped(
          Effect.gen(function* () {
            yield* check(input.cwd)
            const ret = yield* Effect.tryPromise({
              try: () =>
                ripgrep(filesArgs(input), {
                  stdout: out,
                  stderr,
                  ...opts(input.cwd),
                }),
              catch: toError,
            })
            if (buf) Queue.offerUnsafe(queue, clean(buf))
            if (ret.code === 0 || ret.code === 1) {
              Queue.endUnsafe(queue)
              return
            }
            fail(queue, error(err, ret.code ?? 1))
          }).pipe(
            Effect.catch((err) =>
              Effect.sync(() => {
                fail(queue, err)
              }),
            ),
          ),
        )
      }),
    )
  }

  function filesWorker(input: FilesInput) {
    return Stream.callback<string, Error>(
      Effect.fnUntraced(function* (queue: Queue.Queue<string, Error | Cause.Done>) {
        if (input.signal?.aborted) {
          fail(queue, abort(input.signal))
          return
        }

        const w = yield* Effect.acquireRelease(worker(), (w) => Effect.sync(() => w.terminate()))
        let open = true
        const close = () => {
          if (!open) return false
          open = false
          return true
        }
        const onabort = () => {
          if (!close()) return
          fail(queue, abort(input.signal))
        }

        w.onerror = (evt) => {
          if (!close()) return
          fail(queue, toError(evt.error ?? evt.message))
        }
        w.onmessage = (evt: MessageEvent<WorkerLine | WorkerDone | WorkerError>) => {
          const msg = evt.data
          if (msg.type === "line") {
            if (open) Queue.offerUnsafe(queue, msg.line)
            return
          }
          if (!close()) return
          if (msg.type === "error") {
            fail(queue, Object.assign(new Error(msg.error.message), msg.error))
            return
          }
          if (msg.code === 0 || msg.code === 1) {
            Queue.endUnsafe(queue)
            return
          }
          fail(queue, error(msg.stderr, msg.code))
        }

        yield* Effect.acquireRelease(
          Effect.sync(() => {
            input.signal?.addEventListener("abort", onabort, { once: true })
            w.postMessage({
              kind: "files",
              cwd: input.cwd,
              args: filesArgs(input),
            } satisfies Run)
          }),
          () =>
            Effect.sync(() => {
              input.signal?.removeEventListener("abort", onabort)
              w.onerror = null
              w.onmessage = null
            }),
        )
      }),
    )
  }

  export const layer = Layer.effect(
    Service,
    Effect.gen(function* () {
      const source = (input: FilesInput) => {
        const useWorker = !!input.signal && typeof Worker !== "undefined"
        if (!useWorker && input.signal) {
          log.warn("worker unavailable, ripgrep abort disabled")
        }
        return useWorker ? filesWorker(input) : filesDirect(input)
      }

      const files: Interface["files"] = (input) => source(input)

      const tree: Interface["tree"] = Effect.fn("Ripgrep.tree")(function* (input: TreeInput) {
        log.info("tree", input)
        const list = Array.from(yield* source({ cwd: input.cwd, signal: input.signal }).pipe(Stream.runCollect))

        interface Node {
          name: string
          children: Map<string, Node>
        }

        function child(node: Node, name: string) {
          const item = node.children.get(name)
          if (item) return item
          const next = { name, children: new Map() }
          node.children.set(name, next)
          return next
        }

        function count(node: Node): number {
          return Array.from(node.children.values()).reduce((sum, child) => sum + 1 + count(child), 0)
        }

        const root: Node = { name: "", children: new Map() }
        for (const file of list) {
          if (file.includes(".opencode")) continue
          const parts = file.split(path.sep)
          if (parts.length < 2) continue
          let node = root
          for (const part of parts.slice(0, -1)) {
            node = child(node, part)
          }
        }

        const total = count(root)
        const limit = input.limit ?? total
        const lines: string[] = []
        const queue: Array<{ node: Node; path: string }> = Array.from(root.children.values())
          .sort((a, b) => a.name.localeCompare(b.name))
          .map((node) => ({ node, path: node.name }))

        let used = 0
        for (let i = 0; i < queue.length && used < limit; i++) {
          const item = queue[i]
          lines.push(item.path)
          used++
          queue.push(
            ...Array.from(item.node.children.values())
              .sort((a, b) => a.name.localeCompare(b.name))
              .map((node) => ({ node, path: `${item.path}/${node.name}` })),
          )
        }

        if (total > used) lines.push(`[${total - used} truncated]`)
        return lines.join("\n")
      })

      const search: Interface["search"] = Effect.fn("Ripgrep.search")(function* (input: SearchInput) {
        const useWorker = !!input.signal && typeof Worker !== "undefined"
        if (!useWorker && input.signal) {
          log.warn("worker unavailable, ripgrep abort disabled")
        }
        return yield* useWorker ? searchWorker(input) : searchDirect(input)
      })

      return Service.of({ files, tree, search })
    }),
  )

  export const defaultLayer = layer
}