import path from "path"
import { Context, Effect, Layer, Schema } from "effect"
import { FSUtil } from "./fs-util"
import { Git } from "./git"
import { Global } from "./global"
import { Repository } from "./repository"
import { EffectFlock } from "./util/effect-flock"

export type Result = {
  readonly repository: string
  readonly host: string
  readonly remote: string
  readonly localPath: string
  readonly status: "cached" | "cloned" | "refreshed"
  readonly head?: string
  readonly branch?: string
}

export type EnsureInput = {
  readonly reference: Repository.RemoteReference
  readonly refresh?: boolean
  readonly branch?: string
}

export class InvalidRepositoryError extends Schema.TaggedErrorClass<InvalidRepositoryError>()(
  "RepositoryCacheInvalidRepositoryError",
  {
    repository: Schema.String,
    message: Schema.String,
  },
) {}

export class InvalidBranchError extends Schema.TaggedErrorClass<InvalidBranchError>()(
  "RepositoryCacheInvalidBranchError",
  {
    branch: Schema.String,
    message: Schema.String,
  },
) {}

export class CloneFailedError extends Schema.TaggedErrorClass<CloneFailedError>()("RepositoryCacheCloneFailedError", {
  repository: Schema.String,
  message: Schema.String,
}) {}

export class FetchFailedError extends Schema.TaggedErrorClass<FetchFailedError>()("RepositoryCacheFetchFailedError", {
  repository: Schema.String,
  message: Schema.String,
}) {}

export class CheckoutFailedError extends Schema.TaggedErrorClass<CheckoutFailedError>()(
  "RepositoryCacheCheckoutFailedError",
  {
    repository: Schema.String,
    branch: Schema.String,
    message: Schema.String,
  },
) {}

export class ResetFailedError extends Schema.TaggedErrorClass<ResetFailedError>()("RepositoryCacheResetFailedError", {
  repository: Schema.String,
  message: Schema.String,
}) {}

export class LockFailedError extends Schema.TaggedErrorClass<LockFailedError>()("RepositoryCacheLockFailedError", {
  localPath: Schema.String,
  message: Schema.String,
}) {}

export class CacheOperationError extends Schema.TaggedErrorClass<CacheOperationError>()(
  "RepositoryCacheOperationError",
  {
    operation: Schema.String,
    path: Schema.String,
    message: Schema.String,
  },
) {}

export type Error =
  | InvalidRepositoryError
  | InvalidBranchError
  | CloneFailedError
  | FetchFailedError
  | CheckoutFailedError
  | ResetFailedError
  | LockFailedError
  | CacheOperationError

export interface Interface {
  readonly ensure: (input: EnsureInput) => Effect.Effect<Result, Error>
}

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

export function isError(error: unknown): error is Error {
  return (
    error instanceof InvalidRepositoryError ||
    error instanceof InvalidBranchError ||
    error instanceof CloneFailedError ||
    error instanceof FetchFailedError ||
    error instanceof CheckoutFailedError ||
    error instanceof ResetFailedError ||
    error instanceof LockFailedError ||
    error instanceof CacheOperationError
  )
}

export const parseRemote = Effect.fn("RepositoryCache.parseRemote")(function* (repository: string) {
  return yield* Effect.try({
    try: () => Repository.parseRemote(repository),
    catch: (error) => new InvalidRepositoryError({ repository, message: errorMessage(error) }),
  })
})

export const validateBranch = Effect.fn("RepositoryCache.validateBranch")(function* (branch: string) {
  return yield* Effect.try({
    try: () => Repository.validateBranch(branch),
    catch: (error) => new InvalidBranchError({ branch, message: errorMessage(error) }),
  })
})

export const layer: Layer.Layer<Service, never, FSUtil.Service | Git.Service | EffectFlock.Service | Global.Service> =
  Layer.effect(
    Service,
    Effect.gen(function* () {
      const fs = yield* FSUtil.Service
      const git = yield* Git.Service
      const flock = yield* EffectFlock.Service
      const global = yield* Global.Service

      return Service.of({
        ensure: Effect.fn("RepositoryCache.ensure")(function* (input) {
          if (input.branch) yield* validateBranch(input.branch)

          const repository = input.reference.label
          const localPath = Repository.cachePath(global.repos, input.reference)
          const cloneTarget = Repository.parse(input.reference.remote) ?? input.reference

          return yield* flock
            .withLock(
              Effect.gen(function* () {
                yield* cacheOperation(fs.ensureDir(path.dirname(localPath)), "ensure cache directory", localPath)

                const exists = yield* fs.existsSafe(localPath)
                const hasGitDir = yield* fs.existsSafe(path.join(localPath, ".git"))
                const origin = hasGitDir ? yield* git.origin(localPath) : undefined
                const originReference = origin ? Repository.parse(origin) : undefined
                const reuse = hasGitDir && Boolean(originReference && Repository.same(originReference, cloneTarget))
                if (exists && !reuse) {
                  yield* cacheOperation(fs.remove(localPath, { recursive: true }), "remove stale cache", localPath)
                }

                const currentBranch = reuse ? yield* git.branch(localPath) : undefined
                const status = statusForRepository({
                  reuse,
                  refresh: input.refresh,
                  branchMatches: input.branch ? currentBranch === input.branch : undefined,
                })

                if (status === "cloned") {
                  const result = yield* git
                    .clone({ remote: input.reference.remote, target: localPath, branch: input.branch })
                    .pipe(
                      Effect.mapError((error) => new CloneFailedError({ repository, message: errorMessage(error) })),
                    )
                  if (result.exitCode !== 0) {
                    return yield* new CloneFailedError({
                      repository,
                      message: resultMessage(result, `Failed to clone ${repository}`),
                    })
                  }
                }

                if (status === "refreshed") {
                  const fetch = yield* git
                    .fetch(localPath)
                    .pipe(
                      Effect.mapError((error) => new FetchFailedError({ repository, message: errorMessage(error) })),
                    )
                  if (fetch.exitCode !== 0) {
                    return yield* new FetchFailedError({
                      repository,
                      message: resultMessage(fetch, `Failed to refresh ${repository}`),
                    })
                  }

                  if (input.branch) {
                    const requestedBranch = input.branch
                    const fetchBranch = yield* git
                      .fetchBranch(localPath, requestedBranch)
                      .pipe(
                        Effect.mapError((error) => new FetchFailedError({ repository, message: errorMessage(error) })),
                      )
                    if (fetchBranch.exitCode !== 0) {
                      return yield* new FetchFailedError({
                        repository,
                        message: resultMessage(fetchBranch, `Failed to fetch ${requestedBranch}`),
                      })
                    }

                    const checkout = yield* git.checkout(localPath, requestedBranch).pipe(
                      Effect.mapError(
                        (error) =>
                          new CheckoutFailedError({
                            repository,
                            branch: requestedBranch,
                            message: errorMessage(error),
                          }),
                      ),
                    )
                    if (checkout.exitCode !== 0) {
                      return yield* new CheckoutFailedError({
                        repository,
                        branch: requestedBranch,
                        message: resultMessage(checkout, `Failed to checkout ${requestedBranch}`),
                      })
                    }
                  }

                  const reset = yield* git
                    .reset(localPath, yield* resetTarget(git, localPath, input.branch))
                    .pipe(
                      Effect.mapError((error) => new ResetFailedError({ repository, message: errorMessage(error) })),
                    )
                  if (reset.exitCode !== 0) {
                    return yield* new ResetFailedError({
                      repository,
                      message: resultMessage(reset, `Failed to reset ${repository}`),
                    })
                  }
                }

                return {
                  repository,
                  host: input.reference.host,
                  remote: input.reference.remote,
                  localPath,
                  status,
                  head: yield* git.head(localPath),
                  branch: yield* git.branch(localPath),
                } satisfies Result
              }),
              `repository-cache:${localPath}`,
            )
            .pipe(
              Effect.mapError((error) =>
                isError(error) ? error : new LockFailedError({ localPath, message: errorMessage(error) }),
              ),
            )
        }),
      })
    }),
  )

export const defaultLayer: Layer.Layer<Service> = layer.pipe(
  Layer.provide(EffectFlock.defaultLayer),
  Layer.provide(FSUtil.defaultLayer),
  Layer.provide(Git.defaultLayer),
  Layer.provide(Global.defaultLayer),
)

function statusForRepository(input: { reuse: boolean; refresh?: boolean; branchMatches?: boolean }) {
  if (!input.reuse) return "cloned" as const
  if (input.branchMatches === false || input.refresh) return "refreshed" as const
  return "cached" as const
}

function errorMessage(error: unknown) {
  return error instanceof globalThis.Error ? error.message : String(error)
}

function cacheOperation<A, E, R>(effect: Effect.Effect<A, E, R>, operation: string, target: string) {
  return effect.pipe(
    Effect.mapError((error) => new CacheOperationError({ operation, path: target, message: errorMessage(error) })),
  )
}

const resetTarget = Effect.fnUntraced(function* (git: Git.Interface, cwd: string, requestedBranch?: string) {
  if (requestedBranch) return `origin/${requestedBranch}`
  const remoteHead = yield* git.remoteHead(cwd)
  if (remoteHead) return remoteHead
  const currentBranch = yield* git.branch(cwd)
  if (currentBranch) return `origin/${currentBranch}`
  return "HEAD"
})

function resultMessage(result: Git.Result, fallback: string) {
  return result.stderr.trim() || result.text.trim() || fallback
}

export * as RepositoryCache from "./repository-cache"