import * as core from '@actions/core'
import {
  Category,
  DefaultConfiguration,
  Extractor,
  Transformer
} from './configuration'
import {PullRequestInfo, sortPullRequests} from './pullRequests'
import {ReleaseNotesOptions} from './releaseNotes'

export function buildChangelog(
  prs: PullRequestInfo[],
  options: ReleaseNotesOptions
): string {
  // sort to target order
  const config = options.configuration
  const sort = config.sort || DefaultConfiguration.sort
  const sortAsc = sort.toUpperCase() === 'ASC'
  prs = sortPullRequests(prs, sortAsc)
  core.info(`ℹ️ Sorted all pull requests ascending: ${sort}`)

  // drop duplicate pull requests
  if (config.duplicate_filter !== undefined) {
    const extractor = validateTransformer(config.duplicate_filter)
    if (extractor != null) {
      core.info(`ℹ️ Remove duplicated pull requests using \`duplicate_filter\``)

      const deduplicatedMap = new Map<string, PullRequestInfo>()
      for (const pr of prs) {
        const extracted = extractValues(pr, extractor, 'dupliate_filter')
        if (extracted !== null && extracted.length > 0) {
          deduplicatedMap.set(extracted[0], pr)
        } else {
          core.debug(
            `ℹ️ PR (${pr.number}) did not resolve a ID using the \`duplicate_filter\``
          )
        }
      }
      const deduplicatedPRs = Array.from(deduplicatedMap.values())
      const removedElements = prs.length - deduplicatedPRs.length
      core.info(
        `ℹ️ Removed ${removedElements} pull requests during deduplication`
      )
      prs = deduplicatedPRs
    } else {
      core.warning(`⚠️ Configured \`duplicate_filter\` invalid.`)
    }
  }

  // extract additional labels from the commit message
  const labelExtractors = validateTransformers(config.label_extractor)
  for (const extractor of labelExtractors) {
    for (const pr of prs) {
      const extracted = extractValues(pr, extractor, 'label_extractor')
      if (extracted !== null) {
        for (const label of extracted) {
          pr.labels.add(label)
        }
      }
    }
  }

  const validatedTransformers = validateTransformers(config.transformers)
  const transformedMap = new Map<PullRequestInfo, string>()
  // convert PRs to their text representation
  for (const pr of prs) {
    transformedMap.set(
      pr,
      transform(
        fillTemplate(
          pr,
          config.pr_template || DefaultConfiguration.pr_template
        ),
        validatedTransformers
      )
    )
  }
  core.info(
    `ℹ️ Used ${validatedTransformers.length} transformers to adjust message`
  )
  core.info(`✒️ Wrote messages for ${prs.length} pull requests`)

  // bring PRs into the order of categories
  const categorized = new Map<Category, string[]>()
  const categories = config.categories || DefaultConfiguration.categories
  const ignoredLabels =
    config.ignore_labels || DefaultConfiguration.ignore_labels

  for (const category of categories) {
    categorized.set(category, [])
  }

  const categorizedPrs: string[] = []
  const ignoredPrs: string[] = []
  const uncategorizedPrs: string[] = []

  // bring elements in order
  for (const [pr, body] of transformedMap) {
    if (
      haveCommonElements(
        ignoredLabels.map(lbl => lbl.toLocaleLowerCase('en')),
        pr.labels
      )
    ) {
      ignoredPrs.push(body)
      continue
    }

    let matched = false
    for (const [category, pullRequests] of categorized) {
      if (category.exhaustive === true) {
        if (
          haveEveryElements(
            category.labels.map(lbl => lbl.toLocaleLowerCase('en')),
            pr.labels
          )
        ) {
          pullRequests.push(body)
          matched = true
        }
      } else {
        if (
          haveCommonElements(
            category.labels.map(lbl => lbl.toLocaleLowerCase('en')),
            pr.labels
          )
        ) {
          pullRequests.push(body)
          matched = true
        }
      }
    }

    if (!matched) {
      // we allow to have pull requests included in an "uncategorized" category
      for (const [category, pullRequests] of categorized) {
        if (category.labels.length === 0) {
          pullRequests.push(body)
          break
        }
      }

      uncategorizedPrs.push(body)
    } else {
      categorizedPrs.push(body)
    }
  }
  core.info(`ℹ️ Ordered all pull requests into ${categories.length} categories`)

  // construct final changelog
  let changelog = ''
  for (const [category, pullRequests] of categorized) {
    if (pullRequests.length > 0) {
      changelog = `${changelog + category.title}\n\n`

      for (const pr of pullRequests) {
        changelog = `${changelog + pr}\n`
      }

      // add space between
      changelog = `${changelog}\n`
    }
  }
  core.info(`✒️ Wrote ${categorizedPrs.length} categorized pull requests down`)

  let changelogUncategorized = ''
  for (const pr of uncategorizedPrs) {
    changelogUncategorized = `${changelogUncategorized + pr}\n`
  }
  core.info(
    `✒️ Wrote ${uncategorizedPrs.length} non categorized pull requests down`
  )

  let changelogIgnored = ''
  for (const pr of ignoredPrs) {
    changelogIgnored = `${changelogIgnored + pr}\n`
  }
  core.info(`✒️ Wrote ${ignoredPrs.length} ignored pull requests down`)

  // fill template
  let transformedChangelog = config.template || DefaultConfiguration.template
  transformedChangelog = transformedChangelog.replace(
    /\${{CHANGELOG}}/g,
    changelog
  )
  transformedChangelog = transformedChangelog.replace(
    /\${{UNCATEGORIZED}}/g,
    changelogUncategorized
  )
  transformedChangelog = transformedChangelog.replace(
    /\${{IGNORED}}/g,
    changelogIgnored
  )

  // fill other placeholders
  transformedChangelog = transformedChangelog.replace(
    /\${{CATEGORIZED_COUNT}}/g,
    categorizedPrs.length.toString()
  )
  transformedChangelog = transformedChangelog.replace(
    /\${{UNCATEGORIZED_COUNT}}/g,
    uncategorizedPrs.length.toString()
  )
  transformedChangelog = transformedChangelog.replace(
    /\${{IGNORED_COUNT}}/g,
    ignoredPrs.length.toString()
  )
  transformedChangelog = fillAdditionalPlaceholders(
    transformedChangelog,
    options
  )

  core.info(`ℹ️ Filled template`)
  return transformedChangelog
}

export function fillAdditionalPlaceholders(
  text: string,
  options: ReleaseNotesOptions
): string {
  let transformed = text
  transformed = transformed.replace(/\${{OWNER}}/g, options.owner)
  transformed = transformed.replace(/\${{REPO}}/g, options.repo)
  transformed = transformed.replace(/\${{FROM_TAG}}/g, options.fromTag)
  transformed = transformed.replace(/\${{TO_TAG}}/g, options.toTag)
  return transformed
}

function haveCommonElements(arr1: string[], arr2: Set<string>): Boolean {
  return arr1.some(item => arr2.has(item))
}

function haveEveryElements(arr1: string[], arr2: Set<string>): Boolean {
  return arr1.every(item => arr2.has(item))
}

function fillTemplate(pr: PullRequestInfo, template: string): string {
  let transformed = template
  transformed = transformed.replace(/\${{NUMBER}}/g, pr.number.toString())
  transformed = transformed.replace(/\${{TITLE}}/g, pr.title)
  transformed = transformed.replace(/\${{URL}}/g, pr.htmlURL)
  transformed = transformed.replace(
    /\${{MERGED_AT}}/g,
    pr.mergedAt.toISOString()
  )
  transformed = transformed.replace(/\${{AUTHOR}}/g, pr.author)
  transformed = transformed.replace(
    /\${{LABELS}}/g,
    [...pr.labels]?.join(', ') || ''
  )
  transformed = transformed.replace(/\${{MILESTONE}}/g, pr.milestone || '')
  transformed = transformed.replace(/\${{BODY}}/g, pr.body)
  transformed = transformed.replace(
    /\${{ASSIGNEES}}/g,
    pr.assignees?.join(', ') || ''
  )
  transformed = transformed.replace(
    /\${{REVIEWERS}}/g,
    pr.requestedReviewers?.join(', ') || ''
  )
  return transformed
}

function transform(filled: string, transformers: RegexTransformer[]): string {
  if (transformers.length === 0) {
    return filled
  }
  let transformed = filled
  for (const {target, pattern} of transformers) {
    if (pattern) {
      transformed = transformed.replace(pattern, target)
    }
  }
  return transformed
}

function validateTransformers(
  specifiedTransformers: Transformer[]
): RegexTransformer[] {
  const transformers =
    specifiedTransformers || DefaultConfiguration.transformers
  return transformers
    .map(transformer => {
      return validateTransformer(transformer)
    })
    .filter(transformer => transformer?.pattern != null)
    .map(transformer => {
      return transformer as RegexTransformer
    })
}

function validateTransformer(
  transformer?: Transformer
): RegexTransformer | null {
  if (transformer === undefined) {
    return null
  }
  try {
    let onProperty = undefined
    let method = undefined
    if (transformer.hasOwnProperty('on_property')) {
      onProperty = (transformer as Extractor).on_property
      method = (transformer as Extractor).method
    }

    return {
      pattern: new RegExp(
        transformer.pattern.replace('\\\\', '\\'),
        transformer.flags ?? 'gu'
      ),
      target: transformer.target || '',
      onProperty,
      method
    }
  } catch (e) {
    core.warning(`⚠️ Bad replacer regex: ${transformer.pattern}`)
    return null
  }
}

function extractValues(
  pr: PullRequestInfo,
  extractor: RegexTransformer,
  extractor_usecase: string
): string[] | null {
  if (extractor.pattern == null) {
    return null
  }

  let onValue
  if (extractor.onProperty !== undefined) {
    let value: string = pr[extractor.onProperty]
    if (value === undefined) {
      core.warning(
        `⚠️ the provided property '${extractor.onProperty}' for \`${extractor_usecase}\` is not valid`
      )
      value = pr['body']
    }
    onValue = value
  } else {
    onValue = pr.body
  }

  if (extractor.method === 'match') {
    const lables = onValue.match(extractor.pattern)
    if (lables !== null) {
      return lables.map(label => label.toLocaleLowerCase('en'))
    }
  } else {
    const label = onValue.replace(extractor.pattern, extractor.target)
    if (label !== '') {
      return [label.toLocaleLowerCase('en')]
    }
  }
  return null
}

interface RegexTransformer {
  pattern: RegExp | null
  target: string
  onProperty?: 'title' | 'author' | 'milestone' | 'body' | undefined
  method?: 'replace' | 'match' | undefined
}