module.exports = helpSearch

var fs = require("graceful-fs")
  , path = require("path")
  , asyncMap = require("slide").asyncMap
  , npm = require("./npm.js")
  , glob = require("glob")
  , color = require("ansicolors")

helpSearch.usage = "npm help-search <text>"

function helpSearch (args, silent, cb) {
  if (typeof cb !== "function") cb = silent, silent = false
  if (!args.length) return cb(helpSearch.usage)

  var docPath = path.resolve(__dirname, "..", "doc")
  return glob(docPath + "/*/*.md", function (er, files) {
    if (er)
      return cb(er)
    readFiles(files, function (er, data) {
      if (er)
        return cb(er)
      searchFiles(args, data, function (er, results) {
        if (er)
          return cb(er)
        formatResults(args, results, cb)
      })
    })
  })
}

function readFiles (files, cb) {
  var res = {}
  asyncMap(files, function (file, cb) {
    fs.readFile(file, 'utf8', function (er, data) {
      res[file] = data
      return cb(er)
    })
  }, function (er) {
    return cb(er, res)
  })
}

function searchFiles (args, files, cb) {
  var results = []
  Object.keys(files).forEach(function (file) {
    var data = files[file]

    // skip if no matches at all
    var match
    for (var a = 0, l = args.length; a < l && !match; a++) {
      match = data.toLowerCase().indexOf(args[a].toLowerCase()) !== -1
    }
    if (!match)
      return

    var lines = data.split(/\n+/)

    // if a line has a search term, then skip it and the next line.
    // if the next line has a search term, then skip all 3
    // otherwise, set the line to null.  then remove the nulls.
    l = lines.length
    for (var i = 0; i < l; i ++) {
      var line = lines[i]
        , nextLine = lines[i + 1]
        , ll

      match = false
      if (nextLine) {
        for (a = 0, ll = args.length; a < ll && !match; a ++) {
          match = nextLine.toLowerCase()
                  .indexOf(args[a].toLowerCase()) !== -1
        }
        if (match) {
          // skip over the next line, and the line after it.
          i += 2
          continue
        }
      }

      match = false
      for (a = 0, ll = args.length; a < ll && !match; a ++) {
        match = line.toLowerCase().indexOf(args[a].toLowerCase()) !== -1
      }
      if (match) {
        // skip over the next line
        i ++
        continue
      }

      lines[i] = null
    }

    // now squish any string of nulls into a single null
    lines = lines.reduce(function (l, r) {
      if (!(r === null && l[l.length-1] === null)) l.push(r)
      return l
    }, [])

    if (lines[lines.length - 1] === null) lines.pop()
    if (lines[0] === null) lines.shift()

    // now see how many args were found at all.
    var found = {}
      , totalHits = 0
    lines.forEach(function (line) {
      args.forEach(function (arg) {
        var hit = (line || "").toLowerCase()
                  .split(arg.toLowerCase()).length - 1
        if (hit > 0) {
          found[arg] = (found[arg] || 0) + hit
          totalHits += hit
        }
      })
    })

    var cmd = "npm help "
    if (path.basename(path.dirname(file)) === "api") {
      cmd = "npm apihelp "
    }
    cmd += path.basename(file, ".md").replace(/^npm-/, "")
    results.push({ file: file
                 , cmd: cmd
                 , lines: lines
                 , found: Object.keys(found)
                 , hits: found
                 , totalHits: totalHits
                 })
  })

  // if only one result, then just show that help section.
  if (results.length === 1) {
    return npm.commands.help([results[0].file.replace(/\.md$/, "")], cb)
  }

  if (results.length === 0) {
    console.log("No results for " + args.map(JSON.stringify).join(" "))
    return cb()
  }

  // sort results by number of results found, then by number of hits
  // then by number of matching lines
  results = results.sort(function (a, b) {
    return a.found.length > b.found.length ? -1
         : a.found.length < b.found.length ? 1
         : a.totalHits > b.totalHits ? -1
         : a.totalHits < b.totalHits ? 1
         : a.lines.length > b.lines.length ? -1
         : a.lines.length < b.lines.length ? 1
         : 0
  })

  cb(null, results)
}

function formatResults (args, results, cb) {
  if (!results) return cb(null)

  var cols = Math.min(process.stdout.columns || Infinity, 80) + 1

  var out = results.map(function (res) {
    var out = res.cmd
      , r = Object.keys(res.hits).map(function (k) {
          return k + ":" + res.hits[k]
        }).sort(function (a, b) {
          return a > b ? 1 : -1
        }).join(" ")

    out += ((new Array(Math.max(1, cols - out.length - r.length)))
             .join(" ")) + r

    if (!npm.config.get("long")) return out

    out = "\n\n" + out
         + "\n" + (new Array(cols)).join("—") + "\n"
         + res.lines.map(function (line, i) {
      if (line === null || i > 3) return ""
      for (var out = line, a = 0, l = args.length; a < l; a ++) {
        var finder = out.toLowerCase().split(args[a].toLowerCase())
          , newOut = ""
          , p = 0

        finder.forEach(function (f) {
          newOut += out.substr(p, f.length)

          var hilit = out.substr(p + f.length, args[a].length)
          if (npm.color) hilit = color.bgBlack(color.red(hilit))
          newOut += hilit

          p += f.length + args[a].length
        })
      }

      return newOut
    }).join("\n").trim()
    return out
  }).join("\n")

  if (results.length && !npm.config.get("long")) {
    out = "Top hits for "+(args.map(JSON.stringify).join(" "))
        + "\n" + (new Array(cols)).join("—") + "\n"
        + out
        + "\n" + (new Array(cols)).join("—") + "\n"
        + "(run with -l or --long to see more context)"
  }

  console.log(out.trim())
  cb(null, results)
}